Small Engines (Lawn Mowers, etc.): Honda HR21, engine shaft, clutch assembly

Question
I was just given a HONDA HR21 Mower by an old neighbor who doesn't want to mow anymore. I can't find a model number on it anywhere on this mower, only HR21 on the front of the engine shroud. It is self-propelled and has some kind of clutching mechanism on the blade. The mower runs fine and mows decently, the problem is that it vibrates quite a bit when the blade is disengaged. The don't believe the clutch is slipping when mowing. Do you know what might be causing the vibration? There is a little play in the thing that the blade is mounted on, but not in the engine shaft.

Is this expensive to repair? I a very good at fixing things myself, hence the neighbor giving me the mower, but I have never run into on of these before. Just like to know what I am getting into and whether it is worth it.

I was going to give the mower to a friend in need who needs a mower.  

Answer
Hello Galen:

Check the Blade for Balance. The Mower Blades are Balanced. Check the Crankshaft for Being Bent. Remove the Spark Plug and Tilt the Mower so the Spark Plug Hole is Facing Up. Then Turn the Engine and Watch the Blade Bolt. If it Wobbles, then the Crankshaft is Bent or the Blade Clutch Assembly Needs Replacing. You can View a Breakdown/IPL of the Mower and Transmission at this Site Addy, http://hayward.arinet.com/scripts/EmpartISAPI.dll?MF&app=ASP&lang=EN&TF=Mainfram... and Select the Catalog American Honda. I Suggest you Sharpen and Balance the Blade.  Hope this Helps. I am Here if You Require More Assistance. Let Me Know What Happens, Please. Thanks.

Good Luck

Respectfully  

John