Hey Brach,
I will head to Radioshack tomorrow to see if I can get that fuse.
When I measured the 122V (AC) before, it was right after everything had blown and the amp was still plugged in.
In regards to the continuity stuff, I’ve not sure I’ve done it right, so I will explain what I did and what I saw.
With the switch in the off position, with the black multimeter lead on the outside pin of the switch and the red multimeter lead on the middle pin of the switch I got continuity. In every other configuration I tried I did not get continuity — only when the switch was in the off position and touching those two pins did I get anything.
Let me know if I did something wrong and I need to test again.