The tech I took mine to said that the failure was probably due to the old output tubes just being installed without the proper testing and adjustments being done. I can believe that after reading about how cathode-biased amps aren't as "plug and play" as some people (myself included) mistakenly think.
I played the amp for a few hours today and yesterday at medium volumes and it seems to be behaving normally for the time being. I also forgot to mention that the power switch (which was an old russenberger rocker switch) was on its way out and had to be replaced. You could sortof tell...it didn't have that rigid feel anymore.
Overall, both the clean and dirty channels seem to have more bite now. I guess that's probably due to the new tubes. Sounds good to me.
mod evil, do you think that the issues you're encountering with your vc are likely what caused my mishap? My tech didn't say anything about any inherent problems in the output stage design. On the other hand, he couldn't believe how poor the amp's ventilation is. I want to wire a quiet computer fan into the back of it, but I'm not quite there yet. The thing reminds me of an Easybake oven because of the way the board is mounted vertically with the tubes protruding horizontally inward. The passive ventilation scheme does not get the job done
I think from now on I'm at least going to run a fan behind it to blow cool air into the amp.