Reporting question for Switch - Vibrato LDR, for Fender® Amps

Product:
Switch - Vibrato LDR, for Fender® Amps

Question:
Hi I have a 1964 tremolux and the tremolo is not workin I have tried a new tube and footswitch and read the optoisolator might be bad. do you have one for my amp and is there a way to check if it is bad? Thanks Gary