videos like this ->
for F8x which uses basically the same arm, seem like you need a press to remove the stock one and even to insert the new monoball...
i think if i go this route i will just buy new arms (they don't have brushing in) that way its easy to return to stock if its not working out. and maybe find a shop that will press them in for me if need be.
seems like these are the arms, but i am not 100% sure