I had a similar situation last year when I needed repair for one of my Compact 80 monoblocks. They are at least 30 years old. I was able to find biasing info online at VTL but that was about it. I did correspond with Bea at VTL; it wasn't particularly helpful but I thought she made a reasonable effort. I finally found a shop in Nashville that works on tube gear and took both my amps there. The tech was able to test and find two bad filter capacitors and repair the amp without schematics. Good luck!
VTL information
I recently bought a pair of VTL Deluxe 240 monoblocks. The seller didn't have the owners manual. I contacted VTL and was told they don't have any information on amps that age (1993-1997). It has David Manley on the front of the amp too so I called them and was told they engineered them but they were made by VTL. Although they were more helpful still now information. If someone could help me with any information I would greatly appreciate it. I want to get them serviced before trying them and am anxious to hear them.