.............however, before you return them to service PLEASE reach inside the volute and make damned sure the impellor turns freely. I've seen dozens that were tossed as junk and all that was wrong was the impellor was stuck. Remember also, there is a mechanical seal in there, so a little water is safer when you do this. It is true with all brands, so unless you like to disassemble you circulator bank to find out which ones work and which ones are stuck, this saves a lot of time. If you have a seasonal system that sits unused all summer, you could be in the same boat!