I have a Laing SM1212 pump which was working until I replaced the heater. Assembled everything and pump would not run. Took pump out, opened it and it was clean,ran it dry for few seconds. Plumbed it in again-will not run. It is getting power, I can feel it humming and getting warm. Cut off power to save motor.
Are you sure it was pumping water through the heater before you replaced the heater? If the pump was not pumping water through the heater the heater will not operate. If it was operating before the heater was replaced it would be on a seperate hook up from the heater so should have no connection with heater replacement. In some spas the manufacturer will have a built in "summer logic" meaning if the water in the spa gets a few degrees above the set temperature it will shut that pump off. How you can test that by lowing the set temperature.