I've not changed the brushes in mine yet, the m/g isn't even installed but i have replaced many a brush in other dc motors and generators.
My 10ee is a 1942 so yours may be different, i have 4 brushes, 2 each side, a simple wound spring holds the brush agienst the comm. The hard part is going to be the screws that the brush pig tails are connected to the brush rigging with. they look to be about a #10, small but not tiny and are sloted or straight blade. I'm guessing the new brush has forked terminals on the pigtail leads not ring terminals, an advanatage since you only need to loosen the screw and not remove it.
New brushes won't match the shape of your comm, you'll need to seat them. Easily done with silicon carbide sand paper, avoid aluminum oxide it can short the comm, (i've used aluminum oxide in the past without ever shorting anything but it was a gamble and i may have just gotten lucky. The choice is yours).
DO NOT SCRATCH YOUR NOSE OR RUB YOUR FOREHEAD. carbon dust gets every where, and stick to you really well.
You'll need something corse, like an 80 or 120 grit to start then a finer 320 or simillare to finish. The paper is slid between the comm and the new brush and the springs installed. The paper is then pulled thru the brush holding each end of the paper taunt so it forms around the comm. Repeate until you have >75% of the brush formed to the comm shape. You can lift out the brush after a few strokes and look, you'll see the form taking shape. When you've reached the 75% switch to the finer paper and finish with a few more strokes, check them again and you'll see the heavy sanding marks going away.
A small shop vac to clean up the extra dust and abrasive's, a good washing of your hands
Done.
Proper techniques for generators is to only sand in the direction of rotation, dc motors can be sanded pullibng the paper back and forth, a genny should only be sanded the one way. That said i've sanded many a genny brush by pulling back and forth with no ill effects, this was done on comm's of a larger diameter than the 10ee's comm so i really can't comment if the small diameter comm will care or not.
Browse this site, you'll find plenty of info about brushes.
The First Name in Carbon Brush Technology - Helwig Carbon
I've tried attaching a pic, it may give you a view you don't have.