Unless you are very lucky, there are very few places you can get vintage machines serviced. Even if you did find someone with the knowledge and skills willing to do it, the charges for diagnosis, component replacement (and shipping) is likely to exceed the value of the machine. The exception would be if it is a rare and/or a critical piece of legacy machinery a business just can't afford to have out of service.
I found myself wishing there were repair services when I first started to collect vintage computers a few years ago. My aim was to collect classic models and have them all working so eventually I could display them when I retired. I knew nothing about electronics and I must say in retrospect my plans were somewhat naive. I had assumed electronic equipment would store well in dry environments and that if you switched them on years later, they would go. I also assumed that if you received them in working condition, they would stay that way.
This is far from the reality of the situation of course.
This means for most of us, the only recourse is to have a go yourself. I did this with some trepidation but with the help of people on this forum, and a one or two friends who live nearby
I've managed to maintain a working collection. It's taken some doing, but I've learnt a lot and found the process of diagnosing and fixing these old machines is actually a satisfying activity in its own right.
If you have a broken machine and no one to fix it, in most cases you'll have nothing to lose by having a crack at the job yourself. Generally the older the machine the more likely it is to fail, but also the easier it is to fix (no surface mount, no VLSI chips and socketed ICs).
Even if you don't manage to fix it, well, you would have learnt something you could probably use in another repair.
Tez