Black stuff on my axle holder

There is a bunch of black stuff in the axle holders of my punchline. What is it and will it affect play?
i tried to scrape it out but it won’t budge.

just leave it alone, if it aint broke why fix it? and some axles are black, some are silver

try to wear it out with lots of playing. if that doesent were it down and it is effecting the play then mabyz you should contact another expert or good modder PM me if you have any other questions