Bought this amp years ago second hand. I never used it much. Kicked out a couple of time, no sound, replaced the preamp tube once and that didn't really help. Now it will work fine for a few minutes before beginning to make a fizzing sound on each note then going quiet. I have built a few tube amp projects so I'm familiar with some of the components internally. There are some markings inside the amp that indicate the right output transistor board was "new" at some point. I cleaned the pots which seemed to help a little but the problem came back. I'm using a TOA PA wedge with a 15 inch speaker, a horn, and two small tweeters. I use the speakon out with bridge switch engaged. The speaker works well with my ancient Traynor 100 watt amp that requires a 4 ohm load. The resistance of the cable to the speaker measures 7.5 ohms. I know this probably not ideal but should be ok if it's higher rather than lower. I was hoping someone might have experienced some of the same issues and could point me in the right direction. I don't have a lot of money to spend on this but I'm handy with a soldering iron and have a VOM meter, etc. I'm thinking the fizzled sound might point to the preamp section of the amp. Any ideas? Any help would be really appreciated. I know people often say to call Larry Hartke but, really? I think he must be retired by now and tired of hearing peoples problems with this amp, lol.