Last week, I found that my Mono/Poly was dead. Luckily, it was just some blown fuses. After replacing those and powering it up, I found that one of the trimmer pots on KLM-398 was smoking. So, I replaced that as well, which is a little more involved that simply changing a fuse.
If you'd like to see my documentation of the repair, check out the link below. It's also got a little audio demo of my repair Mono/Poly, if you're into that sort of thing...
If anyone has any suggestions on how the repair could have been done better, I'd appreciate your comments.