Here are some extra tips on how to get the best use of my comb tool™
Hold the comb tool over the comb to distribute the weight of your fingers. Hold both the comb tool and the comb at the same time as you sand.
Make sure you don't rub the tips of your fingers on the sandpaper.
To sand down a bulge somewhere in the middle of the comb, find the focal point of the bulge and position the end of the comb tool over it.
Only cover the bottom half of the comb. Apply gentle downwards pressure as you sand. Re-check and repeat as needed.
Most of the sanding happens right under the comb tool. The farther away from the comb tool, the less material will be sanded away.
Positioning the tool like this prevents you from removing too much material at the tips of the tines because there is more material at the back of the comb than at the front.
To flatten a downward facing bow, sand down each side. Position the end of the comb tool over each side.
Flatten the left side and then do the right side.
Then do a quick flattening of the whole surface to even things out before you re-check.
Repeat the whole process as needed.
Position the tool closer or farther from the middle as needed.
One last thing...
Overworking things may build up a bulge in the very middle of the comb.
You may need to lightly sand down the very middle of the comb freehand, then flip it over and do a quick sanding of the whole surface.