I believe the motor capacitor with its bracket fell down and pinched two wires going to the motor. I spliced them back with two blue wire nuts. The motor works again.
However, this made me thinking, can I leave this as permanent solution or is there disaster going to happen if wire nuts come off (there were 2 14 or 16 awg wires that were rejoined)? Should I get Wago connectors instead? Solder? Crimp? Or change the whole harness? What's the best practice?