In reply to stevesmith:
I assume you've done the obvious: checked that all the connections to the cartridge are still attached, unplugged and re-inserted the leads between the turntable and the amp a few times to make a clean connection and the like, and perhaps taken the top off the amp to check that there's not a wire loose?
If there's still no luck, then you're in a bit of a difficult spot. The problem is more likely to be with the amp than the turntable as, provided the platter is still going round, all the wires are attached and there's no unusual noise or smell, there's not a lot to go wrong with a turntable; you could always try using a multimeter to see if there's a signal coming out of the phono leads, of course.
The nearest hifi shop to you that I've used for test, repair and the like is Doug Brady in Warrington; which is a fair drag. Other people may, of course, have used and trust places more conveniently located. There used to be - and may still be - a hifi shop in Lancaster (on Penny Street, I think, at the uphill end) which you could try. Otherwise, it's a judgement call as to how much you like your amp. There's a decent level of support for Naim repairs and upgrades; these folk popped up after a quick google
http://www.witchhatservicing.co.uk (I've not used them; I'm a Linn chap, mostly) but you'd need to balance the cost of a repair, perhaps coupled with a general service and replacement of capacitors and the like to give an all-round improvement against the cost of a new (to you, perhaps) amp, and that's a judgement you're going to have to make.
Sorry I can't be a bit more help! Good luck, whichever route you take.
T.