This is a great guide to hand-lapping tape heads. Nortronics used to make replacement heads for tape decks and other accessories for the tape industries. I worked for an offshoot of the company for a short time and unfortunately didn't see any of these kits in the lab but found this manual kicking around the net.
Interesting. Nearly all the procedures are the same as when we used to have to lap the ends of fibre optic cables after they had been fitted into connectors (back in the 1980s).
I haven't done any lapping yet but there's a few heads I've looked at that look like they might need it. I guess you had to have pretty clean ends on the fibre optic cable to keep the signal moving. My friend gave me a super cool fibre optic flash light, it was for surgical applications but had a blinding light coming out of a flexible cable. I used it for car engine repair back when flashlights were horrible.
