Need help to repair a Kitchen Aid Ultrapower 5 Speed Blender Model #KSB50B4?

I own a Kitchen Aid Ultrapower 5 Speed Blender Model #KSB50B4 that was purchased at COSTCO a few short years ago. All cycles worked perfectly at the time of purchase, but it was never possible to remove the collar from the pitcher's base collar band at the narrowest end portion of the pitcher to allow correct cleaning. I assumed, incorrectly, that perhaps forcing this area to come away from the pitcher by using some kind of instrument or make-shift tool would probably damage the appliance entirely. As a result, I simple took special care to use and clean the blender’s soiled pitcher without ever allowing this lower portion of the pitcher’s collar band to be submerged in water. As time passed, however, it became clearly obvious that some food particles or moisture would be left remaining at the base end of the pitcher where this “collar” portion should apparently have been removable for cleaning purposes. Still unable to ever remove it, however, I had to continue using the blender, which, otherwise, continued to work properly until now. The blender continues to work in any of the cycles except the “pulse” cycle. How may I fix these issues: (1); separating the glass pitcher from the “collar piece of the unit” in order to access all portions of the appliance that require washing after use, and (2) successfully having the “pulse” cycle returned to working order?