EK pumps struggles to start, sometimes doesn't.

So not too long ago I attempted to do a rigid tube conversion from soft tubing. Long story short, the whole thing was a disaster and I scrapped the project and went back to soft tubing. During the project I picked up a EK REVO D5 140 pump/res combo about 3 weeks ago so I could ditch my EK DDC pump as it's not really convenient to find a place for it in my case. Plus, I really don't care for the look of having a separate pump.

It worked fine, at first, but it's crapped out so to speak. More times than not, when I put power to the pump, I can feel it try to kick on 3 times but never does. I've also disassbled the damn thing and watched it do this. Now if I pull the impaler out and put it back in, reassemble the res, and hook it back up, the pump starts up just fine. However, if I cut power and start it back up again, I get the same issues with the pump making 3 attempts to start.

Sometimes if I tap on the side of the pump it will get going, but the issue returns once the pump is power cycled.

Did I just get bad lock and bought a DOA pump or is there something I can do to remedy the issue??

Now the DDC pump I've had for the last year and recently put back into my rig is doing the same thing.

I've ruled out the PSU and MoBo as being culprits. This issue is specific to the pumps. And I cannot, for the life of me, figure out why this is occurring on an older pump AND a brand new pump.

If it's happening to both pumps, my guess its an issue with the loop. I hope you didn't run it dry when disassembled as you can damage the pump by doing so.

Was the gear cleaned before installation and is there any blockage else where in the loop to your knowledge or a stubborn air pocket? What fluid is being used and has it change from its originality?

Anything is possible at this point. A few shots of the loop's reservoir, pump area, tubing and fluid might help us.

Please double check all the pins from the PSU to the pump. Startup is extra current, a not so good pin connection can cause it. Wiggle and restart. Open each connection and make sure the female ends aren't open too fat. Could of been the issue to start with. Got a modular PSU? Plugs off the PSU not just wires coming out?