I'm working on a non reverb Princeton with very low output. Someone had done some work to it before I got it. Everything checks out; the voltages are a bit above spec, all resistors are within spec, good tubes, re-flowed the grounds, cleaned the sockets, etc., etc. Here's the problem; there was a 250k pot in the volume position, so I installed a 1 meg. No change. When I read the 1 meg pot installed in the amp, it reads 215k. If I remove it from the control panel, it reads 1 meg. The left tab is grounded and it's wired correctly. I cleaned the buss and re-installed it with no change. Any ideas?