In this video I walk through the process of adding LED lights to the foot switch that came with my Marshall DSL 40c guitar tube amplifier. This procedure should be the same or similar on many other guitar amplifiers also. This procedure may void the warranty on your guitar amplifier and the resistor values may differ between amplifiers. Keep in mind that the circuit is still closed, however there appears to not be enough voltage to prevent the foot switch from doing it’s job. Perform this Marshall DSL 40c amp mod (modification) at your own risk. If you’re going to try this modification on a Fendrr amplifier or Peavey amplifer, you’d want to go through the same process of determining how the switches work and voltage.