Small Engines (Lawn Mowers, etc.): honda lawn more, honda lawn, fine shape

Question
I have a problem with my Honda Harmony 5hp mower engine.  This is a bit long, sorry, but I am not sure if it may be important.  Last year I foolishly hit a partially buried timber in my yard.  The resulting wobble led me to believe I had bent the shaft.  Took the mower to repair shop to confirm.  They agreed.  I ordered a new engine, and decided to tear the damaged one apart for fun and experience.  Once dissassembled, I found the shaft to be in fine shape to the eye, so I took it to a machine shop and had them spin it, it was fine.  Rebuilt the engine, put on new blades, which I assumed the repair shop had done, pulled twice and I was mowing again.  Needless to say, I returned the other engine, at the expense of the repair shop.  Now for my problem.  Mower worked fine the first two to three mows this year, then my wife used it and reported trouble starting.  Sometimes it will start on one pull and run fine, other times it will start but barely run.  Then you have to shut it off and try again, and sometimes it will run great.  I have been unable to diagnose the problem, and am looking for advice. Thanks in advance for your help.

Answer
It's sounds like you may have debris in the carb.  I recommend you remove and thoroughly clean the carb using a piece of tag wire to push through all of the internal passage and follow up with aerosol carb cleaner.  Other than that, check the blade brake switch to make sure the lever (via the cable) is properly engaging the switch and the choke is properly adjusted so it closes and opens according to the corresponding throttle position.  Hope this helps.