Lucky wrote:
Can't help with the engine question, you might try an NG more geared to
that, like alt.mechanics, alt.lawnmowers, if there are any of course.

With regards to your cotton tree issues, in the future, purchase a
lawnmover slip that will protect it from both the tree and the elements
or else make one yourself out of tarp.

The flotsam from cottonwood trees blows down every spring and floats
about forever. Then, a week after it settles and you think it's over,
another high wind will come up and more tree debris will fill the air.
The problem is not that the stuff settles on the mower but that gets
sucked in, remaining the air for so long to begin with and becoming
airborne again during mowing. I swear that my mower ingests pounds of
the stuff annually and none of its mechanisms are safe from it. And in
my region, cottonwood time occurs during the first intensely dry weather
patches. Fluff mixes with wind-blown topsoil, and it all gets swallowed
by my mower.