You have sufficient vacuum to get everything to work properly after you take care of the leaks.
You might remover the Check Valve on the Vacuum Pump and take a look at it and hose it out with WD-40 (don't use anything like brake cleaner that softens plastic as there is plastic parts inside of the check valve). I was getting like 17 inches Hg of vacuum and it turned out the Check Valve was full of gunk. Cleaning it out with WD-40 cured it and that was like 8 years or more ago.
Ebay shows that there are still expensive kits available but you need 2 kits and a new Check Valve to equal a rebuilt or new Vacuum Pump. It is cheaper to get the whole pump and you also get a warranty.
Other issues.
W123 - Vacuum Pump