[rossb]

chicki I have several aquaclear filters running. I have found that if they are not level they cause wear on the stainless steel shaft that the impeller runs on. Evenutally they will shear it off which renders the motor unit ...landfill. This also causes the impeller to wear and get loose on the shaft ... and the filter gets noisy. You can pull the impeller and stainless steel shaft out with a pair of pliers and buy a new shaft for about $4.00. You can also replace the impeller for about $10.00. They stock them at petland, and most aquarium shops. Once a year or so I pull off the motor, pull out the shaft , clean the impeller and the well where the impeller sits with a brush ( a small tooth brush or bottle brush) and check for wear on the shaft.

I also have several powerheads that have a similiar impeller arrangement that I clean frequetnly as well.

you might try this next time your unit stops (I'm of course refering to the aquaclear).