Recirculating pump not working after water heater replacement

I had my 40 gal hot water heater replaced and now the recirculating pump isn't working. The plumber feigns ignorance. My question(assuming its getting power): is there something that has to be done to the pump (priming?) to get it working again? The pump is a Grundfas.

You may have to remove the heat trap on the hot outlet. It serves no purpose anyway if you use a recirc. My guess is the old tank didn't have heat traps.

My other thought is perhaps some sediment got into the pump and it no longer turns.