SeworDye,
I cannot speak for all the vintage Berninas but my wife has a Bernina Record 930 she got in 2000 when my cousin died. My cousin had it since it was new back in the mid 80s.
It has been a very excellent machine. Absolutely ZERO problems with it. It had not been cleaned or oiled since my wife got it and who knows how long before that until about 2 years ago.
I took enough packed lint out of the bobbin area to make a cat sweater. I oiled it and cleaned it and it just purrs away.
There are owners here that have Berninas from the 600s up and to date I have not ( or at least I don't remember ) heard any complaints about them.
Joe