Thanks to you all. I am feeling much reassured and won't ever make that particular mistake again.
TWL: The test record was toast from the moment I opened it and saw the label torn and spattered, waiting to snag any stylus that ventured too near. To my mind it thoroughly deserved its pulverization. So I can think of this as merely a detour on the way to the trashbin.
Dougdeacon: I'm not quite so far gone as actually to have spent those hours listening to the pink noise. (Though just a smidgen more infatuation and such a thing might begin to seem a rational and attractive use of time.) My patchy system no longer has actual speakers, only headphones (AKG-K1000s, far cheaper than comparably good speakers and more practical in my acoustically leaky apartment). I just stuck the earphones on my ears every once in a while to make sure nothing was going audibly wrong.
Cpdunn99: Possibly so. Not everything sounds gives that treble tizziness, however; and some records (like a set of Couperin trios on ASV Gaudeamus last night) are perfection. The P3 isn't especially friendly to VTA adjustments, but I've got a couple of spacers around and will experiment. Maybe my ideas of perfection need a little exercise.
Kurt_tank: The Glider was what my local audio dealer steered me to, I think because he had had experience with it and not with the other cartridges I had come in to ask him about. I felt a little hesitant about it, but this cartridge was necessarily going to be a compromise between something that would work with the P3 and its RB300 and might also be transferrable (I hope) to what I might get next--except that the more I read the less sure I am of what I ought to or even can get next, so the framework of this hypothetically reasonable compromise has fallen apart. Anyway, it's experience.
Given the state of the rest of my system, I really have no business owning a Loricraft at all. I love it but can't do a proper comparison with other machines, first because it's the only RCM I've used (I took a big jump up from an ancient DiscWasher and then a carbon fiber brush, both of which did a surprisingly good job of keeping my records pretty clean, considering) and second because the unit I got was used when I bought it. I've had some problems with the management of the thread--since more or less resolved, partly by the SmartDevices technicians, who gave the thread tube a good flossing and replaced the jar's hardware, and partly by my own experimentation with the speed of the vacuum head's movement over the surface of the record. But these problems I think I would not have experienced had I shelled out for a new machine. I got the Loricraft instead of a VPI for the same principal reason I use headphones rather than real speakers: a strong desire not to drive my neighbors crazy. But I'm not especially fond of the VPI's shrieking myself. And, maybe more than anything else, I just loved the splendid solidity and admirable ingenuity and general wellmadeness of the Loricraft--a primitive feeling of intense liking that that has me in its grip even yet.
Susan