During the last snowstorm of the season, the venerable MTD snowthrower carved a trench out of the garage and across the driveway, then abruptly stopped moving. The motor roared and the auger turned, but the drive clutch handle had no effect, so I dragged its carcass into the garage and we completed the mission by hand.
Popping the belly plate on the next sunny day revealed the problem: the jam nut (part 34) anchoring the Friction Disk Wheel (part 28) to the Friction Wheel Bracket Assembly (part 32) had gone missing:
Worse, the Wheel’s threaded shaft spent some time rattling around in the Bracket while chewing up its thread:
This would ordinarily be No Big Deal, but what you see of the shaft is all you get: it rotates freely in the bearing embedded in the Wheel with no way to hold it while cleaning up its threads.
Having already promised to replace the Wheel, I installed the new Wheel using a castle nut secured with a generous dollop of red Loctite, then tapped two of its castellations into the shaft’s slot as a mechanical anchor:
I really wanted to lay a nice hard roll pin along that slot through the nut, but there’s no convincing way to secure such a thing without a second nut. Maybe next time?
While I had the drive train apart, the sad state of the Wheel Shift Rod Assembly (part 29) became apparent:
I scuffed up the shiny wear mark, turned a suitable acetal bushing, filled the trench with epoxy, and squished the bushing in place:
The flange might hold it in place against the Frame Shift Bracket (part 18), which snugly contains the rest of the bushing against the epoxy, so the whole affair might outlast the next season’s first snowstorm. We shall see.
A nice new R-clip secures the Friction Wheel Bracket Assembly in place against the old washer:
You might want to insert it the other way, but the black plastic housing above it extends just far enough to thwart your (well, my) desire.
The Smell of Molten Projects in the Morning 
Nice work. You are ready for an early-May snowstorm.
Mary: “No way!”
Ed: “Just you wait!”
This winter, the snow blower relaxed in the garden shed, waiting on a storm with sufficiently low density and high quantity to justify getting it out.
Much of the snow we get is quite wet, and storms with enough snow to warrant machine-assisted removal have to be judged for probability of losing shear bolts.
The past couple of years have teamed up to make the former paragraph moot. We’re in the Exceptional zone. Sigh.
https://www.drought.gov/states/oregon
There was about a foot of heavy snow between Christmas and New Year, but other than that, hardly any white stuff. OTOH, it was cold enough so that anything not plowed out lasted as mini-glaciers into late March.
Just drop a dowel pin in the slot and peen the edges of the slot over it with a cold chisel. Top with JB-Weld for flavor. :)
Well played, Sir!