Good to know you are well and progressing in the world of FarmBot!
Our vacuum pump seems to both suck and blow.
I tested without any tubes attached. I set the pump to run, them placed my finger under each nozzle and felt suction at the “in” arrow and air coming out of the “out” nozzle. I did not try with tubes or needles yet. I did notice that in the instructions, the CAD drawing showed the tube connected to what looks to be the “out” nozzle, but I am connecting it (the tube) to what is marked as the “in” nozzle. But, if as you say, you have tried both, it may be a defective pump. I would guess that if the diaphragm (or whatever mechanism is used to force air) is defective, one possible symptom could be to force and suck air out of either/both.
Maybe take the vacuum pump off and feed it 3 to 5 volts at a workbench so you can better root cause.
I know it is not much, but hopefully this helps. If it is defective, I am sure the fine folks at FB will make it right!
Adding fine folks: @roryaronson @RickCarlino @Gabriel