Back in 2011, I bought a Micro-Nikkor 55 2.8 from a fellow RFFer. He disclosed in the ad that the lens needed relubrication. I bought it, and had it sent directly to APS. $110 later, it was as good as new.
More recently I had my 105 2.5 AIS serviced. I don't have the receipt at hand, but I recall that it was in the $135 range with APS. Incidentally, infinity is at infinity in all my lenses.
Finally, I bought in April 2018 a Nikkor 45mm f/2.8 GN (Guide Number) lens. I sent this off to Frank Marshman, in Virginia. The fee was $95, but the lens is sparkling clean, and smooth to focus now.
I have to put in a pitch for the 45mm GN lens. It's not "just another Tessar". It's a really great one. Sharp even wide open, with no distortion. The GN feature is brilliant. Lock in your guide number, and all your flash pictures will be perfectly exposed. When locked in, you can't focus closer than the correct distance for f/32, which is the minimum aperture with this lens. I use it with my Nikon F and the Nikon BC-7 flash unit. Just keep putting new bulbs in the unit, focus and fire. It's just that simple. (You can do this with less drama using your electronic flash on the manual setting). The BC-7 has two positions on the reflector. The wider setting is for a 35mm lens. The "normal" setting is for the 45mm lens. It shows you how well thought out and integrated the Nikon F system was.