Knobs won't come off Bassman 100 combo

[MstrB]

I am having a problem with a Fender Bassman 100 SS combo. I am trying to remove the knobs so I can remove the circuitboard so I can resolder the input jack. I was using my stew mac knob puller that we usually use on guitars, so I am being gentle and slow but the knobs are pulling the shafts out of the pots! ARRRRRGH! Any one else experience this? I have sprayed a penetrating lubricant on the the other shafts to see if that will help them break free without further damage.

[The Dude]

Just repaired one last week. It left the shop today. I didn't have any problems removing the knobs. I know that doesn't probably help you any, but as far as I know, there's not anything special going on with them. I do recall that all of the nuts were loose underneath the knobs, though.

[MstrB]

its crazy, 2 in a row so I stopped. Maybe a hairdryer to warm the plastic?

[TomCarlos]

Ask the tech of they were glued on for some reason. Be VERY careful in trying to pull off the knob. The pots are frail. You can damage them if you keep pulling on the knobs (which means you are pulling on the shaft).

[The Dude]

I feel for you, man. I've run into it on rare occasion myself and it's not fun. I'm sure you would have looked, but somebody didn't put knobs with set screws on it, did they?

Years ago I had the same trouble on a 32 channel Mackie desk. I called the customer to see if he had any info that might enlighten me. He told me that the knobs kept falling off so their soundman super glued them all on............brilliant! I told him that since that was the case, he could either come and get it no charge or pay for every one of the pots that broke as a result of trying to get the knobs off. He opted to pick it up unrepaired.

[Enzo]

There was a run of pots some time back, and a whole amp's worth of shafts pulled out. At the time fender warranted it. There is no glue. The knobs just seized to the shafts.

Other than heat maybe loosening things, there really isn't much to do but replace pots.

[olddawg]

I've delt with this before when people glue on the knobs by cutting them off with a Dremel tool and a cutting disk. Somtimes blue tape or a piece of scrap cardboard to protect the faceplate. Then replace the knobs. Easier than replacing pots and usually cheaper.

[Zipslack]

Yeah, I can't offer any help about getting them off. I have been able to re-assemble pots that had the shaft pull like that, but Fender's pots are typically all plastic and don't want to re-assemble well. If the hair dryer thing doesn't work, figure in cost of replacement pots and time (check with the customer first - as The Dude mentioned).

Has anybody ever tried using something like WD-40 or Liquid Wrench in situations like this? Would have to be careful about getting it in places you don't want, but may work.

[patlaw]

PB Blaster and Kroll Oil are great for loosening things that are stuck, but if the pots are glued, you're out of luck. You might try tapping them with a rubber hammer to possibly loosen then. It's a L-O-N-G shot.

[g1]

If you get to the point where you are going to sacrifice the knobs or the pots, I would see if I could crush/break the knobs with something like vice-grips or channel-locks first.
Much easier to replace knobs than pots .

[J M Fahey]

I see that often and ordering new pots is not a (sensible) option, plus my motto is: "the PCB IS the amp" .
You can buy all parts over the counter or , worst case, from Factory ... except a new shiny PCB (let alone the work of transfering everything) so I pamper them.

Replacing pots involves desoldering, pulling, twisting, remounting and resoldering , BAD for the PCB and done only if absolutely necessary.

The disposable and cheap part here is the knob itself so I *destroy* them.

A Dremel is "way too good"; besides being slow it can cut through the shaft, front panel, leaves metal dust all over the place, etc. so I consider it only on metal knobs (very rare these days).

I have sharpened a pair cutting pliers (30 seconds at the grinding wheel) so it easily bites on plastic (standard metal cutting angle often slips) and snip chunks off the knob, not straight at the center line but 30% to one side.

By the 2nd or 3rd cut the knob carcass usually can be slipped away if it's just a tight pressure problem or some more are needed if it's actually superglued, but the small glued plastic bits can be taken out with the tip of an X-acto knife.

Of course, if you have to do it 32 or 46 times the mixer must be thrown out anyway , but I first try to pull all knobs the normal way, usually my method is used to deal with a few problematic ones.

Anyway killing the knob is 1/10th the cost or worry of ordering and replacing the whole pot .... plus if they are glued to the shaft they are usually still lost anyway and you have to order more.

Here most customers balk but eventually accept the idea of having a few non original knobs, the alternative is junking the mixer.

[Randall]

I had a Fender Deluxe Reverb Re-issue in recently that had almost all of the knobs seized to the pot shafts from playing at seaside outdoor gigs all it's life. I had to replace all of the knobs, and three of the pots. I attempted to break them off after soaking in penetrating oil for two days, but was not 100% successful.

[olddawg]

I see that often and ordering new pots is not a (sensible) option, plus my motto is: "the PCB IS the amp" .
You can buy all parts over the counter or , worst case, from Factory ... except a new shiny PCB (let alone the work of transfering everything) so I pamper them.

Replacing pots involves desoldering, pulling, twisting, remounting and resoldering , BAD for the PCB and done only if absolutely necessary.

The disposable and cheap part here is the knob itself so I *destroy* them.

A Dremel is "way too good"; besides being slow it can cut through the shaft, front panel, leaves metal dust all over the place, etc. so I consider it only on metal knobs (very rare these days).

I have sharpened a pair cutting pliers (30 seconds at the grinding wheel) so it easily bites on plastic (standard metal cutting angle often slips) and snip chunks off the knob, not straight at the center line but 30% to one side.

By the 2nd or 3rd cut the knob carcass usually can be slipped away if it's just a tight pressure problem or some more are needed if it's actually superglued, but the small glued plastic bits can be taken out with the tip of an X-acto knife.

Of course, if you have to do it 32 or 46 times the mixer must be thrown out anyway , but I first try to pull all knobs the normal way, usually my method is used to deal with a few problematic ones.

Anyway killing the knob is 1/10th the cost or worry of ordering and replacing the whole pot .... plus if they are glued to the shaft they are usually still lost anyway and you have to order more.

Here most customers balk but eventually accept the idea of having a few non original knobs, the alternative is junking the mixer.

Usually with the a Dremel with the right disc on a plastic knob, all you have to do is cut a slice into it. That releases the pressure and it easily comes off. If it doesn't, just stick a flat blade screwdriver into the slice and twist. No matter what method you use its a good idea to protect the panel with something. Also.... When I'm grinding on something like that, I usually have a vaccuum cleaner nozzle next to it.