Camera Clinic Turn Park Station Rd. Chester-le-Street Co Durham DH3 3DY. Tel 0191 388 7001
Luton Cameras Bristol 17 West Street Old Market Bristol, BS2 0DF. Tel 01179 550541
Luton Camera Repairs 49 Guildford St. Luton Beds LU1 2NJ. http://www.lutcamre.demon.co.uk Tel 01582 458323
H Lehmann and Son Ltd 247-249 London Road Stoke-on-Trent Staffordshire ST4 5AA http://www.lehmannsdirect.co.uk Tel: 01782 413611 Fax: 01782 744579
If you are much cleverer than me, you could try a repair using the XA repair manual on the site, but with the problem you describe, it could be almost anywhere. Worth reading though as it may help pinpoint the problem but I doubt it.
This information is a few years old, so they may not be there now or do this sort of repair. You may have to start coming to terms with getting a new XA. Take a look on Ebay to get an idea of prices etc but always check by email with the seller that the camera is fully functional - the shutter works etc.