I am surprised you haven't gotten through to customer service, they've always been prompt when I've needed them. Sorry to hear it.I am also using the GHL 2.1 doser. Two of the pump covers all grinded up on the inside and seized. Stopped dosing my alk. RTN half my sps corals. The other two pumps makes all sort of noises. I tried to contact GHL by email, phone and opened a ticket, no reply. Their support is non-existent. Terrible company. I read on other forums GHL dosers crashed thier tank and people cannot get any warranty service too.