I bought my Atmos a bit over a year ago from this chap, I had been looking for a while and when this one was advertised he stated that the bellows had a date of manufacture marked on them, it was my actual birthdate , had to buy it !.
I was really pleased with the condition and everything. I had chatted with him on the phone first and he said it was a hobby of his to buy, refurbish and service them.
I can recommend him so may be worth contacting him for your service needs.
http://www.atmosclockrepair.co.uk/