bowing keyframe

[Eliot Lee]

Dear List,

    I have the good misfortune to be called back by a guy who has a Tokei 5'
Grand.

    I could not bed the keyframe it either bows in the middle or the ends, I
can't remember which.  No small sanding of the frame could help.  I am
wondering if this was ever done deliberately by the factory?  What could
have caused it to warp?
    Have any of you had this type of experience?  Aside from sanding, what
is recommended to make the frame more level?

Thanks,

Hoping to make more improvements on this next week.

Eliot