At the VHS dub house I worked, each of the recorders would be taken down once a month to have all of the rollers, head drum, and other parts of the tape path that made contact with the tape cleaned by hand by the engineering department. In the head end where the masters were played, we'd do the same thing on the master playback equipment at the beginning of each shift and possibly more frequently if the masters were of less quality or really old. The 1" machines were easy to clean, but the cassette formats were more difficult in having to pull the units out of the racks, remove the cover, blah blah.
At least this is my recollection. <shivers/> the really bad ol' days