This is ringing a bell now.
I bought a Multi-Watt Dual Rec. off of Reverb (the Blackout one that I have now) that had the Kruse Variac mod, even had the Kruse metal plate on the front. I knew the amp was modded and thought, what the hell, maybe the Variac thing would be nice to have. It replaces the Standby Switch with a "Variac" potentiometer and does whatever modification is involved in making that work.
The amp was making that same, or similar artifact sound at the tail end of the notes when I got it. It did this all the time, on all settings, on all Variac positions and not just in a specific scenario, Bright Switch on, etc. I had never owned a Multi-Watt or any Recto for that matter so I didn't know what to expect but I know it wasn't supposed to sound like that.
When I looked inside the amp at the circuit board, I could see that some kind of modification had been done, and I don't know jack shit about electronics or amp modding or anything. I can bias my own amps but that's all I know. I was simply just tracing the wiring from the "Variac" pot and seeing how things were connected. I opened a support case with Mesa Boogie, sent them some audio recordings of the sound and some pictures and they said they could not help me with it.
I contacted Jens Kruse, explained the situation to him and he said that if I shipped the amp back to him he would reverse the mod. I shipped it to him, he reversed the mod, shipped it back to me and it's worked perfectly ever since. I don't remember if he charged me to reverse the mod but I did pay shipping both ways.
May be worth a shot if the modification is reversible.
And since I bought from a dealer, I don't have the previous owner's name. Nor do I expect that dealer to provide that name.
