Well documented issue, overheating, melted cheap wiring, cheap burned out switches made in China, a Dyson, it is not!
Had exactly the same problem with my upright Eureka Model 5893 bagless. Eventually, the handle would get hot, and finally it just quit. When handle was disassembled, the wires were melted and it was toast. Ordered a switch after talking to several repair men. Talked to Eureka, too, and they were absolutely no help. Cheap wiring and switch made in China. Good luck trying to find a switch. vacuum-depot.com has switches, so you might try there, but make sure you get the 3-prong switch (same switch used on Eureka's Genesis). It is Part #27871.
And lots more