Do not give up cookies. However, you should give up using a refurbished kitchenaid. Buying new is no guarantee that what you get will be defect-free (mine wasn't), but it does guarantee you can just call them and send it back and get a replacement all via UPS (which is what I did).

Also, remember we are at a high altitude. Most of the time, cookie recipes don't care, but some recipes are more sensitive than others.