Help with Fluval G6

Hi Was wondering if any one else out there has a fluval G6 on their tank. We have had one on our tank for about 12 months with no real problem. But now it just won't work. It keeps coming up with an "ALERT check impeller motor" message. We have tried everything! At first we could just clean the cartridge and it would start again for a week before it stopped and displayed the message. Then it would be only a couple of days. From there it got worse to running for half a day before showing the message, then to half an hour and now it will start up, pump water for a few minutes and then display the message.

Any one else have this problem? How did you fix it?

Thanks