I have a Yamaha THR10 amp. It fell on the ground and the switch is now stuck in the off position. I'm thinking I can fix it myself taking the amp apart, buying a replacement switch, desoldering old switch and soldering the new switch in place which may involve just a couple of wires.

I've never done any amp work, but I have swapped out pickups and pots in a guitar and have the soldering supplies I'd need. It seems straight forward to me, but "you don't know what you don't know," so I'm just posting this in case anyone can tell me whether there's any special problems, issues, etc. with doing this kind of amp fix that I might not be aware of.

Bernie Sanders for President!
As long as you get the right kind of switch (check the voltage/power rating), I wouldn't anticipate any issues. If you can do a guitar pickup, a power switch should be easy. Sometimes they're on spade connectors so you don't even have to solder.