Hi Debbie, W/D here.
You can certainly repair this mixer yourself. You will need an exploded diagram, and will need to tear it down to locate and replace the damaged part(s). In your mixer, there are two parts that sound suspect. They are the control plate and the control board, numbered #36 and #39 in the diagram (link) that follows. The link that I'm directing you to is very user friendly; you can toggle back and forth between the various drawings and see everything that goes into making a mixer. It's not very complicated to work on. You can use the diagrams as a guide to getting to the parts. Here are a few things to consider, if this is something unfamiliar to you: 1. Print the schematics, and make notes on the schematics as you go. 2. Use a sharpie to mark terminals as to the color of the wires connecting to each. Pictures and sketches are even better, making re-assembly a snap. A cell phone camera may be good enough. You can also mark wires by using painter's tape and a sharpie, showing what connects to where. I generally use all of the above, and it serves me well. The reason to tear it down to the parts mentioned is that there are several versions of each part in the diagram. There is a picture of each part in the parts list, so you will be able to readily identify your part. Also, you may be able to visually determine which part is defective. Since each part runs in the $30 range, you can save some money if you can see that one part shows signs of damage, and the other doesn't. If you can't determine which one it is, replace both. Keep all of the parts that you remove together.
Make sure that the power is OFF before making any attempt to repair/tear down/re-assemble the mixer.
Here's the link. Best regards and good luck, --W/D--http://www.appliancepartspros.com/partsearch/model.aspx?model_id=239779&diagram_id=28194300#d28194300