Small Engines (Lawn Mowers, etc.): Blade housing jumps up and down, spindle assembly, pullys

Question
My father passed away and I got his 8 HP Snapper Easy Rider lawnmower.  It's about 3 years old but we didn't find the owner's manual.  While mowing my grass Saturday, all of a sudden the blade housing of my mower started vibrating and making a terrible noise.  I turned the motor off. We took the housing off the top but found the belt was not broken and nothing was caught in the pullys.  We raised the mower up and nothing was wrapped around the blade.  However, the blade was hard to turn by hand.  My husband saw the grease fitting so he thought it might need greasing.  He greased it and we lowered the mower and when we started it up again it did the same thing.  Also, even though the blade was disengaged it engaged by itself and the pullys would turn and stop and turn and stop.  All the while it was jumping and making a noise.  Do you think we need to replace the belt?  Could the blade be bent?  We don't know what could be wrong since we don't have a manual.  Hope you can help

Answer
Hi Perry,

The blade spindles and pulleys must turn freely.  It sounds like at least one spindle has bearings that are frozen.  You will need to replace the bearings or entire spindle assembly.  There may be other related problems but you will need to start with this.  

Let me know how you make out.
Michael