This is an age 20+ Delta centerset faucet, single "crystal" handle.
Untouched since installed, but needs new seals at this point.
The screw-down cap holding down the inner parts, ball, etc. is frozen, pipe wrench won't loosen it, faucet moves instead.
Any tips on how to get it motivated?
Have a new cap coming from our customer service (lifetime warranty) friends at Delta, they're also supplying new seals & springs. Since I removed the faucet from the vanity top, I'm going to see if soaking it in vinegar will free up the cap.