TBP-1 preamp: plug in foot switch causes amp to be mute

[J M Fahey]

Halfway (practical) solution:
cutting tracks may solve it, but may also add to the confusion.

I would:

* pull the PCB and save it for future use with the proper amp, if ever needed.

* Epoxy proper Leds to case holes.

* screw 4 switches (recommend new ones, leaving old ones in PCB) to case

* PTP/hardwire needed diodes , resistors, whatever, as needed, following TBP1 schematic of course.

* Enjoy.

Having each footswitch clearly visible, on its own, will contribute to success

And youŽll only pay for actual parts needed.

* IF needed, troubleshooting will be straightforward and simpler.

[strato56]

You mentioned that the first three switches work : so modifying that PCB should be quite possible.
Maybe you should draw a schematic and compare it to the original one.