Its one thing to spend a huge amount of time and money on tracking down some 18 year old piece of vintage aftermarket parts, for nostalgia value
But what problems are you having? Not recocking? Low FPS? Chopping paint? Ineffecient? trigger skipping? leaks? stripped screws? Corkscrews?
Old guns are like old cars. When you have problems, people tend to throw parts at it hoping it will get fixed. Fortunetly, for the VM68, there is still a ton of N/OS parts floating around that you can fix most problems. PTP has a good supply of parts. Plus Ron-ASP on ebay.
Lots of airsmiths were making parts, like Chris Mader, and others, but they have all moved on.