It is always a good thing to have your projector/s serviced on a regular basis. This can help preserve the life of the machine and also most importantly prevent damage to your valuable film prints which cant be replaced.
Don't wait until it starts to show faults on projection. It may be to late by then.

There only seems to be a handful of people in the whole country capable of servicing a projector.

Yes Robert it is getting to be a problem here in the UK. All the more reason to service them while we still can.