Posted for "Field, Peter B" <peter.b.field@boeing.com>:

 Bill:
     I'd try heat first.  Strap/clamp it down so as to take out the
 twist mechanically and then heat it up to around 250 degrees.  Most of
 the twist may be in the trailing edge.  I have used the heat gun and a
 hand held surface IR reading thermometer to straighten trailing edges
 and things like that.  You may be able to remove the "twist" that way.
 If you closed out the flap on an uneven surface the twist may take more
 drastic measures.  If you have to split it open you can use air pressure
 as one means. Let me know how you make out.
 
 Regards,
 Pete