My Bosch 5" ROS has recently become very hard to handle. I have had it for
a few years now and have always found it to be quite easy to handle and yet
powerful. However, lately I have barely been able to keep it on the work
surface. I can see that it moves in both the circular as well as random
motions still. I took the pad off to see what I could and found that there
is a rubber ring that rides against the back of the sanding pad to direct
the airflow for the dust collection through the proper ports. I found that
the ring was caked with paint residue. Not thinking that this was relevant,
I cleaned the residue off anyway before I put it back together. It was much
more manageable, for a while. It went back to its difficult behavior fairly
quickly. I took it apart again and found that the ring was again covered
with paint residue, (BTW I was trying to sand out some primer). I cleaned
it again and it ran better. I do not understand why the paint residue would
cause it to behave the way that it does. Has anyone had the strange
problem? I was thinking about putting a very light coat of silicone spray
on the ring to see if that would prevent the paint from sticking to it.
Does anyone have any better ideas?

SteveP.