Have to buy a new motor... gear is not sold seperatly. $297.00 from the dealership (plus tax)

or.
Wait a month or two, there's a guy who is making new gears for us (he is using my sunroof motor to make prototypes). Talk is they will done in the next month or two at a cost of about 60 bucks. He is making them out of some hard resin type material, not the crappy nylon Hebasto used. I wouldn't buy a new motor from Ford becuase (sorry to say) it will strip out again. I've had the motor (gear related, ofcourse) replaced 3 times under my ESP warranty. And it went again a month ago... luckily Jeff came along with an idea and some progress is goin.
Hope that helps.