Hi Dongsok, 
A quick response, but hopefully of use:
I just recently sold my Joseph Norris single (Norris was a student of Challis’, and my instrument was almost identical in design to Challis instruments). I worked on this harpi extensively. 
While I can’t any longer take pictures to show, I can tell you which components in the mechanism to adjust. 

First check the capstan at the right-hand end of the jack guide rail- use a thin screwdriver. 
There are then 2 more capstan screws: one of either side of the brass piece which pushes over the jack guide rail. They are used limit off/on position.

If no results:
Each pedal actuates a rod, the vertical movement of which is of course eventually translated to the lateral motion of a jack register.. 
The top of this rod should be threaded and should house a screw. This screw can be used to adjust the length of the rod. 

I pass by Lincoln center often enough that I could stop in and check it out if you have no success.
good luck !
-Landon

> On Oct 20, 2016, at 6:53 PM, Dongsok Shin <[log in to unmask]> wrote:
> 
> To anyone with knowledge of John Challis harpsichords. The Metropolitan Opera in NYC uses their serial number 81.393 harpsichord regularly. 16x8x4 over two manuals with pedals to turn registers on and off. Does anyone have any diagrams or information concerning how the register mechanism is constructed, and what to do about registers that don't seem to turn on or off completely? I'd appreciate any information or resources anyone might have about this! 
> Kindest regards, 
> Dongsok Shin
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tributors and not necessarily  those of the list owners  nor of the Uni-
versity of Iowa.  For a brief  summary of list  commands, send mail to
[log in to unmask]  saying  HELP .
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