My ejector pump is making a low humming sound but nothing is ejecting. It's a Hydromatic with I believe a diaphragm switch. I checked the fuse box, all seems ok. I plugged the pump cord directly into the outlet (bypassing piggyback) and same result (humming). The diaphragm switch is submersed in water but the pump is not (so not a lot in there). I believe it was humming for 30+ minutes but then stopped and then started up again a little while later (that's when I discovered what the humming sound was). So it seems like it is switching on and off but it is definitely not working right. What are my next steps to diagnose the issue?