A couple of weeks ago I started to have an issue with on of my VTA ST70's on power up. Occasionally I'd get static on the right side, and I noticed that one of the power tubes was not lighting up. OK I know all of you are saying well replace that power tube, which is exactly what I should have done. I'm not sure if it's the experimenter in me or the cheapskate in me but I could coach that tube into firing and all would be fine.
Last night I powered up and the same filament issue happened but with a new twist. My rectifier put on a light show! The fuse blew and I successfully took out a power tube and a rectifier. After replacing both my amp is running fine.