This is a process of elimination problem. You've already verified you have vacuum at the pump. To be thorough, verify you have vacuum at each of the fittings coming off the pump.
Then disconnect the circuits and plug them off one at a time. I would start by testing the circuit to the...
How confident are you in the pump rebuild? I haven't rebuilt a 1hdt/hz pump but (going by some old memory) when i rebuilt my 2h pump a common error was putting the vanes in backwards.