I bought mine that had been recently rebuilt so good to know there's a video to help me out with any issues!
Check seed cups for both the large and small box. - both somewhat fragile. Coulters can wear out in certain soils. Springs that put force to press wheels.
Those are main things I can think of that I've had to mess with thus far.
Had to use one Southern States had for rent, twice, when the NRCS Great Plains drills were booked way out. Got crap stands both times. Swore I'd never use a Tye NTD again. YMMV.