Yes, we switched plastic last winter to comply with some new regs in Europe on recycling and electronics. The new plastic has presented some difficulties for us. It cools differently and can laminate and the layers seperate and blister. It took us a while to figure out exactly what was happening. We do test every pump individually but the test lasts less than a minute, the wattage is verified and that the pump runs. This problem takes a while to occur and may not show in a pump that was just made. The problem is not visible on parts inspection so that is how this happens.
I will replace the motor if you PM me an address to ship to.