Product review (5 stars): Not a quicky fix but worth it
I have had my KA mixer for probably 35 years.  I this day and age we don't repair appliances all that much....usually replace.  I really didn't need to replace this lever as it was only the black knob that had broken off.  The lever itself was working fine.  However, knobs weren't available so I went with the whole thing.  How hard could it be, right?  Well, an engineer friend and I put it together and it took a while.  I found instructions on the internet and followed them painstakingly step by step.  I am notoriously meticulous about following instructions and reading the manual for everything.  Even so, this was a challenge.  We did it.  Lots of black grease and swearing later, I had a new lever with a nice black knob.  While the mixer was turned upside down for repairs I noticed how deteriorated the rubber feet were so I sent for replacements of those too.  I say do the repair, change the lever, but follow the instructions you can find on YouTube and do it carefully.  Or find an appliance repairman.