Hi David,
You could try these Crown Classics - 16D Crown Yard, Crown Road, St Margaret's, Twickenham, Middx. TW1 3EE.
Tel/Fax: 020-8891-6101.
Just around the corner - they are currently repairing my GT6 MkI and seem to know their stuff.
Alternatively, the fuse that is blowing may simply be too low a rating - check your manual.
NiG
http://www.niginthecar.net