Thx for the tips on the plug gauges. Ordered from Enco and
found they have two applicable coupons until the end o' the month -
GAMEDAY for 15% off $99+
-and-
KICKOFF for free shipping on $99+
So my ZZ set, "on sale" for $79, plus a made in USA adjustable wrench and a pair of scouring pads, came out to less, to my door, than many other vendors charge for the gauges alone, sans shipping.
I'm assuming these imported gauges are the same as all the other rebranded, non-MUSA sets.
Anyway, I'm back on my way to figuring out why I can't hit the broad side of a barn.