Quick post - sorry, did not check past writings that address this.

But I have already done the disassemble (Stephanie - NO DISASSEMBLE!!) and clean of that microscopic thing. Yeah, it helped, but still tracking issues from left to right afterwards. (Thank you, BTW, for the one who put up that extensive How-To I found on Google with pictures of the process and all the indiv. components and everything. Great confidence builder for the first timer who must take the plunge and worries he'll muck it up.)

What helps just as much, and only takes seconds, is a decent blast of compressed air.

Just use your a blower nozzle to get right up to the trackball and bezel, and blow the heck out of the thing. I go maybe 60psi, and do it while I'm turning it in all directions, circling around with the air gun at all different angles. This is the second time I have used compressed air to restore functionality and it works very well.

I almost always keep my 8310 in its case when in my pocket (and out too), and with clean hands as much as possible. The trackball has issues, there's no way around it.

Try the compressed air, it works.

... or if you have VZW, take it into the VZW store (one with tech support), and they will pop in a brand new one in less than 5 minutes for free. Worked for me!