This set is covered in Sams 2594
A later similar version is in Sams 2711
Its a way over complex design. They used about 75 small parts
to do what 20 parts could.
A few notes were scratched in the manual.
1) Dead set R467 open. Pulsating channel display R426 open.
2) Q503 ( H drive ) is circled. T502 noted with "cold joint"
After the visuals check Q405 & Q501 for dead short. If you
get a short E-C lift 2 legs to see if the short is the transistor or
on the chassis.
73 Zeno
LFOD !