You can get a service schematic for US$9.95 from Hifimanuals.
Soundcraftsmen was a great outfit - I was in their Santa Ana factory several times in the 80's - getting emergency repair work done, or picking up new amps. One time, their lead technician warranty-repaired an amp (while I waited) that we had dropped a probe into, and shorted out! I still have 5 of their PM series 800W amps in service in ATE - driving transformers from 40 Hz up to 100 KHz.
I was saddened when they were purchased - then shut down.