GMT 1675 24hr hand issue

[GMT993]

Firstly Hello everyone and thankyou for hours of very intresting and informative reading over the last few weeks.
I picked up on this forum to try and find some information on a problem I have with my 79 GMT Master 1675 Pepsi, (which i bought off my father some years ago now when he upgraded to a GMT Master2-sons rates of course!!) and have now become totally hooked on the vintage Rolex scene.
Even to the point of now looking to add a 70's Sub (hopefully a RED) and start a modest collection of Vintage sports watches! (dont tell the wife!)
The problem was not noticable at first but is with the 24hour hand being 1 hour fast on the bezel markings compared to the normal 12 hour hand. Is this a problem that can be sorted on a service (which as long as the watch has been in my family has not been done!) or is there something broken that will need parts replacement?
Also any advice on where in the UK is the best place to go for servicing and repair work of vintage Rolex's?
Thanks in advance for any reply's and I look foward to your comments if the picture uploads