I inherited a well-maintained Yard Machines 6HP self-propelled mower
from my home's pervious owner. It's loaded: electric start, convertible
bagger, all the goodies.

But the self-propelled speed is VERY SLOW. Good for a 75-year old man
shuffling along, but for me at 27 it's kind of taxing. Holding in all
the levers is actually starting to hurt my wrist after 45 minutes! Even
my dad at 57 decided "this thing sucks. Lawn mowing should be fun!" I
agree.

Any way to make these things move faster? Gear changes, etc?