you mill off in front so the arms can be moved further forward ,
giving less caster
I do it with a blade sharper tool : 2 stone discs turning to sharpen scissors and so on
just hold the arms against it gently and be very carefull or you will mill off to much
and hold it verticaly and horizontaly straight
and get the same amount at each side !
you should calculate +- 10 mm large cut to pass by the towers too
I will try to post today pictures
sorry batteries down