Sharpening the blades. The idea is to turn the blades backwards across sandpaper
remove the hub-cap and E-rings from each wheel
remove the wheel and pinion gear

just for practise, put them back on.
Now take them off and go to step 2
Inventory
Left SideRight Side
hub cap
E-ring
Wheel
Pinion Gear
Pawl
hub cap
E-ring
Wheel
Pinion Gear
Pawl
2) Make a note of which way the Pawls face
flat to front? or flat to back?
2.a) Remove the Pawls from the rectangular slots and "reverse" their directions
Swap the Pinion gears
(Move left pinion gear to the right wheel and the right pinion gear to the left wheel)
Replace the wheels and the E-rings.

Be careful. Now you are in reverse gear! The blades turn bottom to top.
3) Insert a sheet of 220 grade sandpaper over the cutter bar and under the blades. Cut a second sheet to fill the whole width of the cutter bar.
Tape the sandpaper to the bottom of the cutter bar
If necessary, adjust the cutter bar so that the cutter bar blade has light but firm contact with the reel blades across the full width of the reel blade
Caution: Do not over-tighten

Now, mow the sidewalk! Push the mower up and down a smooth surface that has no grass. Notice how the blades are in reverse and are rubbing the sandpaper, and that the blades are getting sharper....(They are getting sharper, aren't they?)
After a few minutes of adjustments,
Remove the wheels
reset the PAWLS
return the gears to their correct sides
Replace the wheels and go cut the grass.