How can I fix my Waste King SS4000 waste disposal unit? ?

My waste disposal unit started making an unusual noise. When I looked down the mouth of the unit, I saw that one of the blade pivots had some vertical slack, that allowed the blade to rise up above the travel stops on base plate.
Is it possible to tighten/adjust/renew the pivot to reduce the verticle slack ? I assume this requires the removal of the head unit to gain access. Is this something that a DIY person can do or does it take a specialist ? The model number on the plate is SS4025.

Colin
September 2010