Well, here's my used Hobart-era K5SS update.
The only obvious mechanical fault was the bowl lift mechanism. It was sagging in the lifted position pretty bad. The L-shaped bracket on the bowl lift rod inside the pedistal has a hole in it that is somewhat larger than the rod, and it had forced it's way half way over the cotter pin. I reassembled with an M6 washer that is a tight fit around the rod between the bracket and the rod, and torqued down the spring a bit more. It snaps to the top quite well now.
The bowl, flat beater, whisk, and spiral hook i bought on ebay for $50 shipped turned out to be 5.5 quart rather than the advertised 5 quart. The 5.5 is wider, so the bowl, beater, and whisk don't begin to fit the K5SS. Well, I could modify the whisk. I received an apology, a full refund, and a request to throw them out. Near as i can tell, these parts belong to the KSM55 model. There seems to be only one other 5.5 quart lift-bowl kitchenaid, and it has a fancier bowl.
Initially i wasn't pleased with the sound of the motor or the speed regulation. Some parts of the internet suggested that the "control board" (plastic panel with electrical connections, some of them spring loaded) could be at fault due to metal fatigue, which, uh, i don't think that was it. But the contact points were visibly worn and fouled.
Bought the replacement part anyway. Turned up today. I note that the upper set of contacts on the original version are copper on some kind of white metal, and the replacement are copper on brass.
I also finally managed to score a bowl appropriate for the K5SS on local classifieds today for $35 cash.
After removing the original part, I took a closer look at the mechanical governor assembly on the back of the armature spindle and noticed that the little barrel weights had worn flat spots where they rest against the frame of the assembly, so i rotated them 180 degrees. I assume this will make them move a little easier.
I now have it running with what i assume to be normal performance.
I made an experimental batch of potato pizza dough in it. So far I'm not exactly impressed.
The spiral hook i have seems to measure 6.75 inches long. I've just now remembered that i actually do have oversize calipers so i could measure it with some precision, will get to that later i guess. But this seems to be, among the spiral hooks available on amazon, the size given for hooks said to be compatible with the K5SS.
Did i mention that the kitchenaid website is no help? It's negative help. Search for an older model, the hits are pages for accessories where someone asked if it fits it, and got the answer that it does not. Except when the model number is nowhere on the page at all.
No trouble finding the service manual for the K5SS that was published pre-whirlpool but it doesn't have accessory specs. The only user manual i can find is obviously in reference to a modern reproduction by whirlpool. The graphics are too good. And they don't give a part number for the hook anyway.
For that matter, the bowl i found is stamped "made in korea" so it is most likely a more recent Whirlpool part. Seems to fit perfectly, near as i can tell.
The (presumed) KSM55 bowl doesn't fit between the arms on the stand at all, and the flat beater, hooked up to the planetary, strikes the body of the mixer. The whisk fits in the K5SS bowl but strikes the side of the bowl. I could bend it. I ordered a new one instead.
Anyway.
With 160g of cooked, riced potato flesh and 210ml of water in the bottom of the bowl, the tip of the spiral hook just barely dips into the surface of the liquid. Barely skims it.
The bosch um3 hook doesn't exactly scrape the bowl either, but this was targeted for near 800g of dough which is a pretty normal batch size for me in the bosch, and it's less bullshitty in the bosch. In either the plastic bowl or the deluxe bowl - the deluxe hook comes a lot closer to scraping the deluxe bowl fwiw. The longest arm in the deluxe setup is only a few mm from the bottom and walls.
There's a somewhat expensive stainless steel spiral hook for KA mixers on amazon that is, iirc, 7.5" long? After some more research i may buy it.
Edit: 7.3 inch.
https://www.amazon.com/gp/product/B0BHS3BF3N/?tag=pmak-20
