Hey all, I went to play on my B-12-XT the other day, only to find that neither channel 1, vibrato, nor the echo are working. All of these things worked last time I pulled the amp out. All of the tubes were lighting up, and channel 2 worked fine (but again, no vibrato or echo). Both guitar and accordion channels worked on 2, but not 1.

Does anyone know what could be causing this? Is it something simple like a loose wire? Here are a couple pictures of the amp in question, as well as a schematic I found but can't read too well.