Vac Unit Only Turns Left

I'm not a professional, just a pool owner like you, who's had the same problem. It's more than likely a gear issue, but check first. It's easy to take apart (there are on-line demonstrations also) There is a gear box inside.  Blow into the opening on the side the gears should turn easily and make a whirring sound if not replace.  Sometimes debris can get in there and clog it. If this isn't a problem then the medium gear/turbine could be worn. If your cleaner is more than a year old it is possible. There is a "medium gear/turbine rebuild kit. It's easy to do. Get parts online because they are at least half price of pool stores.  This was the issue with my pool vac.  I installed the kit and it works fine.  But beware, my experience has been that such a repair is a regular occurance maybe once every two years.  I got the kit for $37 and pool store selling it for $60. Hope this helps.