Makita HR4001C rebuild with a new armature. 

Thanks. The white stuff is hilti high temp grease. Makita also have the same grease. It's yellow but it only comes in small 30ml tubs. I use the hilti grease as it comes in 1kg pots.

I actually used hilti gear grease here. Makita do have their own but hilti sell it in 1kg tubs