Re: Water pmp leak
Frequently, IMO, things are "NOS" because someone once tried it, found it was defective, and put it back on the shelf. No doubt they intended to return it or whatever, but simply forgot (or left the company, or died). Then someone else came along, bought up the old inventory, and listed it on eBay.
Some years ago, a friend bought a "NOS" alternator on eBay. It was fairly close by, so we drove down to pick it up. The seller waived at a whole rack full of old alternator boxes; but every single one I looked at showed signs of having been installed once (like a shiny spot where the mounting bolt clamps). Sure enough, the one my friend got didn't work, right out of the Lucas box. The seller gave him a refund without complaint (but I'll bet it got sold again).
The pump I got with TS13571L appeared to be original, and had certainly been unused for 25 years or so, but didn't leak. It actually worked fine, until I "borrowed" the pulley to try out a "high tech" pump that I've had on the shelf for 15+ years (one of the very first ones on the market). Evidently I didn't get the pulley mounted solidly enough when I went back to the original pump, as the shaft broke a few weeks later. Next time I'll use Loctite! (The overheating problem turned out to not be the pump at all.)
Fortunately, the replacement pump from Moss (around 1990 as I recall) off my wrecked TR3A still worked fine even after 5-6 years of inactivity. It's the type with the pulley permanently mounted (so no worries about it working loose).