My alleged improvement to the upper bearing ring in our American Standard Elite kitchen faucet didn’t survive nearly as well as I hoped and began leaking through the o-ring seals after the usual year. The 0.4 mm polypropylene shim ring apparently stuck to the nylon bearing ring, wore down to a 0.1 mm thick ribbon against the base, then let the o-ring wear out as usual.
The black gunk around the top of the upper seal area has the consistency of hard plastic paint, although it’s most likely rubber particles from the o-ring burnished against the bronze base by the sliding PP shim ring:
Remember Nisley’s First Rule of Plumbing: Never look inside your water supply pipes.
As before, the o-rings wear on their inner diameters, indicating that they turn with the spout around the base.
For lack of anything smarter, I removed as much of the debris as feasible, installed new seals, reassembled the faucet in reverse order, and ordered another set of parts.
If I hadn’t done such a great job of reinforcing the underside of the sink deck around the mounting rings, to the extent I’m not sure another faucet base else would fit, I’d be far less reluctant to start over.