Maintaining old kit always becomes so expensive that it is only worth while as a preservation argument. The choice then is to give up or replace. Cine cameras would probably provide a good Phd thesis for someone on the survivability of domestic goods from the 20th century.
A point will come where it will be cheaper to make a camera from new. Probably not so difficult with modern computerised machine tools, rapid prototyping and the other manufacturing techniques coming up the back straight. Of course, one could wait until the 'replicator' appears
