Napoleon 1401 insert: blower motor & wiring

My 2yr old (no warranty) Napoleon 1401 wood stove insert has been working well until last week when the right side blower started whining. Thinking it may be jammed a little, I gave the stove a light (honest!) whack with my hand and there was an explosion of electrical sparks and no more action by either motor. I'm quite handy, so I just opened up the covers and found the right blower difficult to turn by hand; and one broken, brittle wire to the rheostat. Upon removing the blower/motor assembly from the stove, a closer look shows blower motor gunked up with dust.

Question #1. Is this a job for WD-40, as long as I keep it from spraying on the blower's rubber gaskets? (see photo)

I see no reason why the wire broke and fried. None of the other wires appear damaged by heat or abrasion. ALL the internal electrical wires say "American Wire and Cable, AWM, 125deg Celcius, 600V, Style 3173, 18 AWG." (see photo)

Question #2. Is this a type of high-temperature wiring? Would, for example, Home Depot carry it? Electric supply?

Thanks,
Theodore.

Update: *looks* like the wire may have fried due to poor design (LISTEN UP, NAPOLEON!). There's electrical arc damage against the sharp edge of the internal baffle (see far right photo). Looks like the wire exits the rheostat vertically and has been abrading against this sharp metal edge for some time and it finally cut through (when I gave it a whack). Thankfully, the entire stove is grounded. I'm sure the hard-to-turn fan probably did cause an overcurrent as well. But it all lines up where the break ocurred.
P.S. thanks for the advice. I oiled the motors properly. No WD-40!