Mark III (Blue Stripe) Combo Power Switch Issue

[drlemonator]

Hi folks!

I just picked up a Mark III combo, blue stripe, 60/100 watt model and I am looking for a little guidance with an issue I am having. When I got it home and plugged it in, it was running in the 60 watt mode and was sounding fantastic! Played it for about 30 minutes or so running through the controls to check everything out and everything was working as expected. I then went to test the wattage switch and after I had switched it to 100 watts, I noticed a significant loss in output from the amp, and it sounded somewhat tinny. I switched back to 60 watt mode and the issue was present there as well, only the amp was quieter (as you would imagine it would be running at a lower wattage). After fiddling with it and doing some basic troubleshooting (nothing seemed out of order), I flipped the switch back into 60 watts and it was back to working. Flipping it back into 100 watt mode caused the issue again and I have not yet been able to get it back in either 60 watt or 100 watt modes.

Unfortunately, where I am located there are not a great deal of amp repair techs available, otherwise I would take it in and have someone look at it right away. I'm just wondering if anyone here has had an experience with this or a similar issue, or has some tips or clues to troubleshoot this particular issue.

Thanks!

 

[Fastforded]

No expert but sounds like a bad switch. Maybe try and clean it with electrical contact cleaner? Like deoxit

 

[drlemonator]

Thanks for the reply! For sure, it's very possible. I'll be going through and cleaning pots and switches soon. This is the first time I've had an amp like this and was unsure if something like this was indicative of maybe a bad tube or tubes, or something else.