Can an autohelm linear drive unit be user cleaned?

[Raven]

I have a Raymarine autohelm system that has not functioned since I bought the boat. From the beginning, I suspected that the problem was sticking brushes in the type 1 linear drive unit. I finally got around to giving the unit a couple of smacks (the bigger hammer approach) and things freed up inside. The autohelm began functioning again, albeit somewhat intermittently. Two questions:

1) How quiet is a type 1 12v linear drive unit typically? (Mine sounds a bit like an electric motor that isn't quite getting all its juice.)

2) Is the drive unit something that can easily be serviced by the user? (I suspect that Raymarine would say no, but I'd like to hear user experiences. In particular, I'd like to get at the brushes and make sure they are making proper contact.)