Small Engines (Lawn Mowers, etc.): Lawn mower cutting too low, blade height, spark plug wire

Question
Hey Mike. Bit of a bizarre situation. I always keep my lawn mower on the highest setting so as to only take a little off when I cut . Lately however the mower has been cutting the grass shorter even though I have it on the highest setting .  I have checked several times to make sure it is on the highest setting and it is. The wheels are fine, I checked underneath the mower and as far as I can see everything looks ok. Blade is sharpended. I am perplexed..any thoughts?

Answer
Hi John,

I assume we are talking about a push mower.

The only thing that could have changed, is the blade height.  For some reason it may have dropped lower.  Disconnect the spark plug wire and inspect the blade and crankshaft.  Look for up and down play in the shaft or blade holder.  Check for the blade being on backwards.  

Let me know what you find.
Michael