Hi Hugh and welcome to the club!
Yes indeed, sticky buttons on 3200/4200 is a classic issue!
I have heard of people using thinner and scraping back any damaged bit, then applying a clear coat (matt finish) lacquer. Needs a bit of faith I think, but if you have a steady hand and patience the results can be very good.
For main dealers you have Graypaul in Nottingham.
McGraths in Hertfordshire are excellent if you want a Specialist. I am sure others may have experiences with others nearer to Lincolnshire.