Weird noises from silvertone

[Ptron]

I've got an amp that makes weird noises fairly regularly. I've attatched a clip since it's a little hard to describe, but if I were to describe it I'd say it's sort if a squeeky, staticy thing. The amp is a solid state Silvertone 1465.

-None of the controls seem to affect the sound.
-Did the chopstick thing, several times, no effect
-I replaced all the electrolytic caps on a whim. Didn't change anything.
-Bringing the amp up on a variac after recapping, I noticed the noise gets a lot worse when the voltage is a little low. 80-90V really gets it going. This is what I did to make the clip since the noise is too sporadic otherwise.
-I posted clips a couple years ago of a freinds wurlitzer electric piano a few years back that was making similar noises. It was suggested by someone that it sounded like RF interference. Could that be what's going on? My only other guess is internal arcing in a component, hopefully not the output transformer.

[Ptron]

No takers? I misleadingly refered to the output transformer in th OP. It's not really an output transformer but rather a phase inverter...er, I guess looking at the schematic, it's not even a phase inverter but just splits the signal to both halves of the output stage. Anyway it's my best guess as to where the problem lies. My thought is if it were RF interference it would be more likely to come from the floating inputs but since none of the controls affect the noise it's apparently happening later. Here's a link to another thread that has a schematic in it. http://music-electronics-forum.com/t23072/

[Ptron]

Dragging up an old thread here but I finally got around to figuring out what was wrong with this amp and thought I'd mention it in case it helps anyone. It appears to have been the 270ohm, 5W cement resistor labeled R23 in the linked schematic. Maybe it was cracked internally or something, who knows, but the noise went away when I replaced it.

[Jazz P Bass]

Now I have to ask what led you to that specific component.

[Ptron]

I followed reasonable troubleshooting procedures like I should have done in the first place , before I went through and replaced all the electrolytics (oh well they were 40+ years old anyway). I disconnected the cathode of C13 and the noise was still there. I disconnected the cathode of C15 and it went away. Solder joints were already reflowed from replacing the caps so I started to replacing things one by one in the Q3 stage and checking after each one so I would know the culprit. The caps were new so I only ended up replacing a few resistors and bingo. I'm glad it wasn't the transformer. I don't imagine a replacement is very easy to find.