Ian P
I can recommend Nick Gauntlett who is in East Sussex and is an accredited watch repairer on the BHI site where his contact details can be found.
Most 1960's quality watch types are easy to service. However, from the 70's onwards, even quality Swiss watches, started to use plastic parts, especially in the date change area, which deteriorate with age and spares are difficult to come by. This was mainly to reduce cost as the competition from quartz watch makers took effect.
Counter intuitively, spares for early watches can be easier to get hold of than for more modern Swiss watches where supply of parts are restricted to approved repair centres. I believe to become an approved Rolex repair centre you have to go on a month long Rolex training course and buy something like £80k's worth of tooling from them.
CS