@Andrew O'Neill
In context of repair/reliability viz Hasselblad, another point occurred to me today.
Starting with the Hasselblad 501C/M and thereafter, they introduced a coating material called "palpas" that was used internally in the body as well as on the barn doors on the side facing the film back.
There was/is a known issue with the palpas cracking badly. I have a 501C/M that has this, whereas my 500C/M does not have the coating, and hence the problem.
According to everything I have read, it seems that palpas is either impossible or very difficult to replace, BUT ... it seems not to matter. The cracked coating appears to have no effect on image production.
If you absolutely want to avoid this issue, get a 500C/M which never had the coating in the first place.