Copied from my FB post to here in hope of an solution...
"I have replaced a fader in my APC 40 and screwed it back together and it still works.
But now I am trying to map a whole new deck/setup and all my faders are giving a max value of around 40 when fully up, not only the faders but also the rotaries need extreme twisting before they get to higher values...anyone got some idea what went wrong?"
but it's back together again