Quick answer on those cheap magnetron’s is no, the typical failure is the filament shorts to the copper block, though you do get a short circuit forming in the connections to the outside, that white plastic block contains 2 feedthrough capacitors, and they can fail. however there really are only a few variants of the magnetron, and by far the most common styles are in the cheap microwaves, meaning pretty much any salvaged microwave magnetron has a good chance of having the right combination of orientations. So long as the mounting base orientation, the fin orientation and the power connector orientation are the same so it physically fits, the new magnetron will work.
Typical causes for fuse blowing are failed transformer, especially the cheaper ones wity CCA wire, and by far the most common fault is a switch failure in the door, there are 3 microswitches in the door area, and either one is faulty, or the plastic mountings are faulty. Another is dirt in the cavity of the magnetron, though that normally leaves a big pile of soot in the area, and also a failed fan or lamp can blow the fuse.