I put new ultrex on my 921 last August before I had a chance to use it I had a health issue and it didn't go in water till April. Got to lake and foot pedal wouldn't move. Local MK service center replaced the sensor there have been issues with. Now I have been out and I thought trolling batteries were bad and they were 6 years old so made sense they were bad. I replaced last weekend and went out today. Batteries lost all power again. This is about 4th time motor been used. I checked the prop when I got back and it is tight to turn and is not smooth when rotating prop by hand. I took off prop and everything looked ok. No line etc. seems to me trolling motor is binding and running down batteries?