Product review (5 stars): Perfect Knob Fit for Me: please do your research
I ordered this knob as an exact part number provided by the manufacturer.  My knob order arrived very quickly packaged in a bag noted with "Whirlpool factory certified parts".  Visual inspection showed the knob appeared to be an exact fit so therefore I was very surprised to find it did not seat very deep on the stove knob stem.  The knob was very wobbly and not secure at all.  A closer inspection with a flashlight inside the knob hole on the back I could see a little plastic shelf that was much shallower than my original knob.  I contacted a friend of mine who repairs appliances and he mentioned folks sometimes need to remove a metal sleeve from the know stem to get a good fit for replacement parts.  Sure enough I removed that sleeve and the knob seated all the way onto the stem.  A perfect fit!

I attached a picture of four of the metal sleeves I removed so you can try this out too if you have the same problem as I originally had.  I also attached a picture of the bag each knob came in.  I strongly suggest anyone buying knobs must do their research for the exact replacement part.  Letter/number markings on the knob back are not necessarily the p/n and multiple different knobs can have the same letter/number marking, but are in fact completely different manufacturer part numbers.  I hope this helps at least one other person who has the same experience.