Ampeg Reverberocket R-12R

[dkirk]

I recently purchased a cosmetically mint Reverberocket, S/N 001478, from the original owner. There is no audible output from the speaker when amp is powered up - no hum - no reverb crash when amp is rocked. Pilot light works and all tubes glow normally so heater circuit is working. Tube compliment is all original factory equipment.

I plan to replace the power supply filter capacitors as standard practice, but would anyone be able to pinpoint the problem area in the R-12R circuit just from this problem description?