top rack not cleaning on kitchenaid

[rhyno]

Top basket not cleaning dishes. Spray arm not turning, but seems to be getting adequate flow through upper tube. I cleaned lime/crud off of arm, tubes,etc. but still doesn’t turn. Even with garden hose spraying full blast into the tube, the arm sprays water out all holes, but wont rotate. It seems to leak alot between where spray arm rotates and stationary piece. Is there a seal between the two? Do I need a new arm, or new arm and stationary peice arm screws to? Thanks, Ron