If you want to process a run-of-the-mill engine like that one and get it out of the place fixed, the quickest way in my experience so far, is to keep a set of "known good" comparison parts. So, first do the obvious simple tests: does it have spark, does it have compression, will it run briefly if primed with petrol? Usually the problem is obvious at that point, but if you suspect a problem that only arises under load or after warm up, change the component you suspect is at fault with your comparison part (in this case, the Magnetron, but more often, the complete carburetor/fuel tank/air cleaner assembly). Give it a decent test run with the comparison part installed, and if the fault has gone, you know with high confidence which part was at fault. Do not leave the comparison part on the engine though, or you'll no longer have a known-good comparison part for next time. Remove it, empty the fuel out, clean it, and put it away safely.
