Emiel, you don't have to unscrew anything to swap tubes, just (gently) pull down on the tubes.  Take notice of how each tube is oriented in its socket, though, as they only fit in one way.

Thanks, JD, I'm gonna leave it as-is for now & maybe experiment once I have a viable back-up amp.

Thanks, Blues, was just informed 250pf - 270pf is good (RF's values).  I have a 390pf on v2a & a 330pf on v2b for now...we'll see how it works out.

Thanks for all the help!

Well, I replaced the resistor, but it was a bust, the problem remained.  Nik advised I should remove the snubbers, so off they came & now I'm back in action.  Only question is, is there any harm in running the amp at gig volumes for a while until I receive some new parts in the mail?

Yes, sorry, I meant to type the 5uf cap and the 180k resistor that follows it (precedes the 100kL pot).

After chasing the power supply to V2 down, I tested the 150k resistor that feeds the 5uf/180k...measurements are out of range, badly.  So, tomorrow, off to the electronics store for a new resistor & then back to rocking!  (Hopefully...)

Thanks, Blues, I appreciate all your help.  I'm new to all this stuff, so tracing connections is very frustrating.  A member of the Amp Garage & TGP known to most D-style players has advised that perhaps the 4.7uf cathode bypass cap has shorted...now to find that & trace the power to V2.

FWIW, Here are my pin voltages on V2:

Pin 1:  185v
Pin 3:  1.645v
Pin 6:  4.29v
Pin 8:  4.28v

Argh!!!

Update:

Every tube I've tried produces the same results.  Pin voltages are off, though, so other than touching up some solder joints on V2, I'm at a loss...

Any other suggestions?

Thanks!  I'll do that later today.

Yeah, I've replaced v1 & v2 & replaced he PI with a known good tube. Thanks, tho!

So, at rehearsal today my 50w OTS just cut out. After troubleshooting tubes, speakers, etc, I switched the OD off at the pedal. To my surprise, I had sound again, just no OD. The PAB still works, but even with the pedal disconnected I cannot manually switch to OD-I get no OD sound at all, just silence. OD off, even with PAB, sound. Anyone care to help me out, suggestions or whatever. Thanks!

100' of cable?  Excessive?

Well, I"m not familiar with the Xpression, but in terms of the Intellifex there are "input" and "output" knobs.  However, for me, its just easier to set the unit to 100% wet & use the Fuchs loop to interface as a parallel mixer (I don't have to mess too much with the programming aspects of the Intellifex this way). 

Yeah, the Intellifex does run an internal parallel mixer, but I had been using the Fuchs before & I'm comfortable with it.  Plus, I hadn't really figured out how to tweak the Intellifex until last week (first rack for me), and figuring out that there was no global kill dry took me a bit.

Well, here it is, my completed rig...

50w Modded OTS (snubbers, cap values, etc)
2x12" Hermida ported cab w/Emi RWB & WGS ET-65
Furman PL-Plus
Ceriatone C-Lator
Korg DT-1 Pro
Rocktron Intellifex
(Not shown)
Fuchs Tube-FX-Loop (for parallel loop interface)
Crybaby Fasel
Tech21 Midi-Mouse