i need to find out what type of diode i need for a fender metalhead 4 button footswitch, but its all burned up so i cant read it and fender doesnt want to give out the information just sell me a new footswitch. the circuit still has continuity but because of the burnt diode, the remaining buttons arent working properly. how do i find out which diode i will need? or at least where to find a circuit schematic?

 

If you know the polarity try a 1n400x series diode. Higher number for x the better.