So, I've got this old cheap HP Scanjet 2400 flatbed scanner for a couple of
bucks, but with a minor, yet unpleasant, mechanical problem.
After scanning, when the mobile head was returning to the original
position, it was stopping at around 2-3cm from the resting position,
continuing to make a noticeable noise as the stepper motor was trying to
move it without success.
The cause was simple: the ribbon cable that connected to the mobile head, was bending and getting caught in between the bottom piece and the head. I've tried disconnecting it completely and bending it in the opposite direction, however this didn't really help. In the end, I've applied some silicone lubricant (I have a spray laying around that I usually use in my car, for rubber gaskets and stuff) on the ribbon cable. This makes it slide easier under the head, and it's less probable that it'll get caught. After a few tests, it seems that this hack is actually working :)
Next task: test how the scanner in Linux (I'm using Debian on my ThinkPad)