Lego 42043 Model B issues

[mikis]

So I've recently built model B from scratch (taking everything apart and not using anything from model A) of Lego 42043. And after I finished itI noticed that my pneumatic pump is not working as intended, it stutters and then stops. I though it may be some pipes in crane that is blocked so it cant pump, but no everythings fine, then I rechecked gears and loosened them so they make as little friction as possible yet nothing changed... 

In model A the pump is going so fast even when its not pumping air to the crane, but in model B (the one I built) it cant even pump for 2 sec when connected to crane. 

So what im asking is, has anyone gotten this problem where in model B  the air pump is not working as intended and is there a fix without rebuilding the whole trailer?

[Maaboo the Witch]

Make sure all of your hoses are fully connected. My 42053 had an issue with air flow when I motorized it; turns out I hadn't pushed the main hose onto the connector enough and it kept getting compressed by the engine cover when it was closed. Pushing it on the rest of the way solved it.

[1gor]

Well I had even more idiotic thing - forgot to recharge batteries  and I thought that motor was gone...