Today I removed the pump cover assy of my 10 month old 2217 Eheim filter to clean/replace the upper white filter pad and to add additional filter wool. The filter has been operating since last January and It was also time to open and clean the impeller, chamber, associated parts.Minimal accumulation was evident in the impeller assy. However when reinstalling and bleeding the filter I noticed that this ultra quite pump had developed a moderate humming noise.I disassembled the pump assy again and eveything seemed to be placed correctly. I would appreciate any info regarding causes for the condition. I have just ordered a new shaft and bearing kit for this pump thinking that that would be the logical approach?