For anyone reading this, do not under any circumstances install the FCC metal spring posts nor metal brush hood screws in your Systema motor
. The risk of error and short circuit via the end bell is extreme, even the most seasoned Systema tech could do it, the average DIYer has a worse chance.
In fact, if you buy anything, buy just the armature, you do not need any other parts, and if the 2.5 brush hoods are any indicator, you will have problems.
I also recommend the 30% silver brushes from Systema, and unless FCC has seriously changed their construction (the pictures show their old carbon brushes), then there is no need for them.