It's a Marshall DSL50 valve guitar amp with the report "keeps blowing fuses and there's a funny smell".
Let's open it up. The output tubes checkout at very low emission using my Mullard MkIV valve tester. So whatever else I find, they need replacing anyway.
One of the valve bases is a bit black and sooty, and so is the socket that it came out of. Better take a closer look. Let's get to the PCB.