Thought I would share this little insight for those running older G25s.
Mine has had potentiometer problems repeatedly as it is a good 7 years old and well used. So today I picked up a G27 for $160 and according to the reviews there is little technical difference. However.....
I just ran a few tracks and set pb's on many of them, mainly due to the accelerator potentiometer that had had a small stutter no doubt but, the difference in wheel feel is vast. I now have a very noticeable feel of what the tyres are doing and can respond much better to it. The wheel is smooth and solid where as the old one clattered. I can only assume that wear and tear has reduced the ability of the old wheel gradually over time.
The new one has given AC a new lease to my driving so if you are running a very old one, an upgrade may be just the thing.
Also, you might already know ( I didn't) that you can adjust your physical wheel rotation settings on the fly using a combination of the buttons on the gear selector -