, sorry to hear that your having problems with your new KA mixer. Since it is under warranty, contact them immediately and tell them about your problem with the stir speed not working. The KA website is at: http://www.kitchenaid.com/flash.cmd?/#/page/home. Click on Customer Care>Contact Us> and the toll free phone number is listed to speak with someone. You can also look under the Warranty & Service Plans to see what KA will do for you. I've extracted parts of it here:
Hassle-Free Replacement Warranty
We’re so confident the quality of our products meets the exacting standards of KitchenAid that, if your mixer should fail within the first year of ownership, KitchenAid will arrange to deliver an identical or comparable replacement to your door free of charge and arrange to have your “failed” mixer returned to us.
Your replacement unit will also be covered by our one year full warranty. Please follow these instructions to receive this quality service.
If you reside in the United States and your KitchenAid® mixer should fail within the first year of ownership, simply call our toll-free Customer Satisfaction Center at 1-800-541-6390, 8 a.m. to 8 p.m.,
Monday through Friday, 10 a.m. to 5 p.m., Saturday, Eastern Time. Give the consultant your complete shipping address. (No P.O. Box Numbers, please.)
When you receive your replacement mixer, use the carton and packing
materials to pack-up your “failed” mixer. In the carton, include your
name and address on a sheet of paper along with a copy of the proof
of purchase (register receipt, credit card charge slip, etc.).
I hope this helps. Good Luck with KA! - Howard, Burke, VA
If this solution has been helpful, please rate it, thanks! - hslincoln