I got mine today, my first dosing pump. Are the heads kind of noisy? Sounds like plastic on plastic grinding. Pump #2 and #4 didn't work. The motor turned but the head sat still. I pulled the head off and moved the crease in the tube and now they work. But seems very shady that the motor shaft is just wedged between the plastic wheels. Is that how it should be?
I've got one pump head that doesn't seem to work on a brand new unit, sounds different then the others when running. Contacted Jebao a week ago and still haven't heard anything. How did you pull your head off to fix it, I tried but afraid I might break it.

