Mellotronists

Hey all,
   Is there any way for me to "unwarp" some of the keys on my 400?  Only (strangely 
enough) the top third of the keyboard is warped noticeably, but I've got some humdingers 
up there in the top octave.  I hear there is some sort of screw at the back of the keys to 
assist in this?  Any suggestions (other than sending it one of the experts)?

Max