Where can I get a replacement plastic gear for the front motor?

I called Shark and told them what the problem was and gave them the date of purchase,and it was only 14mos old they sent me a new motorized brush head for 1/2 price. $10.96 and free shipping.

The small sprocket on the motor split. I repaired it by removing it and cleaning it thoroughly, carefully applying good old JB Weld, clamping it so the crack was completely closed and letting it sit overnight, actually 2 days. Then I pushed it back on the motor. It held! It is still working great after about 6 months.