
Ben,

Since you're obviously adept enough to understand how the trackball works,
the only thing short of repairing it that I can think of is a thorough
cleaning of all the parts, and then checking for the proper placement of
the little blue rollers. Since they aren't fixed in position on their
stainless steel pins, you might try sliding them into a slightly different
position. On my PowerBook 100, I can slide them almost completely out of
contact with the trackball. In fact, one of the notes from sumex on fixing
the trackball advocates sliding the roller so that its _edge_ contacts the
ball, not the center cylindrical area.

I've done this with my PB100, and it does seem to improve the feel, but
needs to be adjusted from time to time. I just popped open one of our
office's PB170s, and while there isn't as much latitude for movement, one
could still adjust the roller slightly. If your PB140 is the same it might
help.

I would suspect the most likely culprit to be a slippery blue roller. If
you can take it out, clean it with a mild soapy solution, or isopropyl 
alcohol. Also, be sure the ball is grease-free.

If you drop the ball in minus the retaining ring, roll the ball and see
if it is actually causing the axle to spin. 

If all this still doesn't solve it, then maybe a new one is in order. :-(
It could be an electrical connection, in which case replacement would be
necessary. But my experience with both mice and trackballs has been that
dirt has been the normal problem, not an electrical malfunction.

Hope this helps,

Murray
 
