The F90X - they're pretty robust and generally its quite hard to find a bad one on ebay. You probably wouldn't pay more than £50 for one. So its uneconomical to repair (Or maybe its time to upgrade to an F100)
Originally Posted by namke
The F4 is almost certainly worth getting a CLA done on it, and no doubt once its had a bit of TLC it'll be good for many more years. Aztech (As mentioned by Myself and Brook above) have a standard rate of £86.25 + 8 quid postage, and probably the same to get it to him by special delivery. So £100 all in.