I have a Kustom 300 P.A. head and I can not get any sound out of it. everything inside looks good, caps are not swollen, nothing seems burnt,. i can not find any thing listed as 300. Is this similar to other models and can I use a different schematic to check it out. The main problem is the power switch. the wiring on this i white, white w/a black stripe and red. i can not find any such colors on any of the schematics I have found. It did work until the switch went bad. Thanks in advance for any help.