Hi @scm - I just got my Modwright 9.0X PSU moded to use tube rectification. I am ready to try some vintage tubes. There is a white ceramic resistor right next to the tube socket. Tubes with wide bases (like the coke bottle style RCA 5R4GYs) seem to tilt the resistor a little bit. Not a lot but surely noticeable. Modwright assured me that this was not a problem - but my OCD is kicking in to high gear. What was your experience like? See pics below.
https://imgpile.com/images/C3jlIl.jpg
Thanks!