Not sure what the problem was with the pumps you are installing.....we have only had to replace one pump in seven years of installing ADI products and it turned out the clients wizard electrician of a son did not have sufficient voltage to the outlet.......that will burn a pump out every time( I left with it plugged into the outlet already on the side of the home) I should have checked after he installed it....but we replaced the pump anyways......He just paid alot more for his next service visit
We require any client that has us install a water garden or low voltage lighting system to run a home run to the panel and have a separate circuit for each transformer we set.....or we don't do the project, period.
I am sure you have a voltage meter to check each installation. We always check line voltage.
The pumps in our display ponds I believe are about 7 to 8 years olds and have run 24/7/365 for that entire time and no problem.
The other thing that can cause pumps to burn prematurely is people not cleaning their pads or debris bag on a regular basis.....at least weekly......You should never restrict flow into a pump and outflow shouldn't be restricted either, although won't burn the pump as quickly.....