I am unfamiliar with the Vigor one specifically, but most vacuum
pumps are at least close so hope this helps. First, the air filter,I
can not stress enough the importance of keeping a fresh one in there.
Unusually they are mounted internally. You should have a sight glass
near the drain plug for the oil, if not maybe on the back of the
machine? The proper oil level is when the sight glass shows the oil
at the half full point. I would also recommend using one of the oil
flushes, especially since it sounds like it sat for a while. I know
Rio sells it, it's on the same page as the oil, but I imagine most of
the suppliers also sell some form of flush. I would also check all of
the lines, especially near the "switch" from vacuum to cast to make
sure they aren't crimped or collapsed. Once again hope this helps.