Yep - we had our Samsung repaired a while back - it worked, except it didn't cook at all. Got a local shop to check it out and repair it - 1K Baht for a new magnetron. If we'd known the repair price beforehand I'd have bought a new one, as the thing cost less than 2K Baht a few years ago - and we don't really use it a lot, either.
The magnetron is apparently the most expensive part to replace.
Good luck with yours.... ????