I'm finnaly getting around to this project. The amp has very very low output after accidental open circuit of speaker leads at close to max output..previously working fine after power supply re-capping. I sent the OT to Mercury Magnetics and they say the OT looks fine for high pot, etc. Though OT does not show any over current damage, they (Mercury) suspect that there could be a chance that the problem is a carbon trace (arch over damage). This type of problem would appear to cause an intermitent problem and I don't think it's the failure mode.
I was so sure the OT was blown that I didn't check out any other possible problems except tubes. Can I power up the amp without OT and tubes and check B+ voltages? Can't see why not. I assume you start at the supply and work towards tubes. If supply voltages check out, I may need to find a second source for OT since Mecrcury may only be able to provide rewind for this application ($350)
Also looking for net wisdom on grounding (three prong power cord) this amp. Seems pretty straight forward.
Thanks,
george