I could not help noticing no one has addressed the safety micro switches that may still be used in this modern age (fixed a lot of them in my time ) . ‘Micro’ is a misnomer , they are large enough to spot easily . They are in the door latch assembly . Could be as many as 4 involved .
A smack to the side of an oven causing it to work points to a problem in the safety function of the door . I would use a meter to confirm function of a switch , taking note of the contacts being N.O. (normal open ) or N.C. making the switch operate to measure N.O. contacts can be awkward …DO NOT do this plugged in… Now , the door switch mechanism can get worn and nothing you can do apart from building up worn cams or such will work . That case is not to be bothered with , send to recycle .
However new(ish) units may have a bad switch but strange readings may require you need to disconnect at least one lead from a suspect switch . Getting some switches out can be a mechanical puzzle HEAVY FORCE should NOT be needed . LOW resistance is absolutely required for a reading . If a contact shows anything above a small fraction of an ohm it should go in the bin . There can be a lot of current flowing and needs to have a low impediment to that . More modern units maybe not and can get by with slight resistance BUT normally should be as close to zero as can be . On older units I have seen blowing main fuse (usually a ceramic 15 amp,confirm blown with meter) caused by bad switches only .
PLAY SAFE …let unit sit for a few minutes after unplug before grabbing things , that large cap CAN be lethal . Pay no heed to Eansor’s coment about 110volt being nothing , YES you can use a finger to detect live wire BUT there are cases of people’s muscles getting locked and you CANNOT let go . If you have heavy calloused fingers not much current would flow and get away with it . NOT the case if you grab 2000 volt charged cap .
Just some thoughts … pardon the long-winded reply .
Hugh