Jim. I had the same problem with my Eheim Pro 4. I did not have the E series. Here is my experience.Mine was about the same age and I went thru all of the troubleshooting guides and then some and it would not pump water much at all. Contacted Eheim and they never got back with me. Some day when I have time I will take the head totally apart and see what is going on. I could not find a complete new pump head only parts. MY Eheim would quit pumping water and I would stop it and then restart it and it would pump water. I cleaned it monthly. Changed filter pads, cleaned hoses, checked for internal leakage and checked seals. The pump head just seemed to gradually loose power. Hope you have a back up filter just in case. I always keep a aqua clear 110 available for just these reasons. Hope you have better luck then I did. Bought a Fluval 406 and no problems so far.