Kh director making popping noise

[elcapitan1993]

So I set up my kh director it was working fine then all of a sudden it started making a popping noise during testing and the test never works correctly and it does it when I try to vent reagent tube
Here is a video of what it does

 

[vetteguy53081]

Check your foster pumps connected to motor drive
Sounds like one is slipping