I have a Maytronics Dolphin Encore pool cleaner that is giving me issues. When it is turned on it goes forward for a few seconds, then reverse for a few second then stops. The impeller is free and clear, but is not spinning. It would normally purge excess air through the top and start cleaning, but it is no longer doing that. . I was wondering if anyone here has had a similar issue with their Dolphin Encore pool cleaner..