What kind of contractor would I need to service or replace pull down attic stairs?
It looks to be exactly like a garage door. I take it lowering the stairs tensions a spring attached to the drums so it is easier to raise. Exact same system as sectional garage doors. The springs can be very dangerous to someone unaware of their potential. I think you should look for someone experienced with sectional garage doors, they will understand this system immediately.

If the rollers are hard plastic or rubber, the system could be made quieter by going to softer rubber. Applying foam to the closure panel could reduce any drumming effect, but will take careful detailing to keep it out of the way and looking attractive. Rubber padding could be added to stops to limit banging. A certain amount of noise is the nature of the beast, unfortunately.