Small Engines (Lawn Mowers, etc.): Self Propelled Drive

Question
I have a Craftsman Model 917.377790 rear self propelled mower with Honda engine.  I think it is just a slipping belt, but I have noticed that when I engage the drive on the self propelled that some time the left tire spins and the right doesn't right away.  Is this a slipping belt or a transmission issue?

Also same mower has a blade clutch.  Can these were out and slip.  It seems that when I get into very much grass at all it clumps.  I was only cutting off about an inch and it cant mulch it in.  I was wondering if the blade is slipping when it gets a load.

Thanks

Answer
The issue with the wheel not engaging is more likely related to a sticking drive pawl.

You can carefully take off one wheel at a time and clean/lube the pawl and/or pinion gear.  ONLY do one side at a time and make sure you pay attention to the part locations and how they are assembled so you can put it back together.  A digital camera is a great tool to use as you dis-assemble the drive parts.

Let me know if cleaning/lubing the drive pawl/pinion fixes the problem.
Eric