Hello,  A Simplex action was the first one I rebuilt back in the
mid-1980's.  At that time replacement wood valves were available from
Player Piano Co. in Kansas in a "Simplex Rebuild Kit" that sells for
$473.00.  Although the company is in liquidation due to the death of
Mr. Armstrong, they are continuing business with the remaining
inventory, for now.

On page 32 of their catalog [PDF page 30], item #682 or #682P is what
you will need, just measure the size of the valve and order accordingly.
They are selling at the costs listed in the catalog, so a set will cost
$159.00 or $164.84 plus shipping and handling.

The catalog can be downloaded at
http://www.playerpianocompany.com/catalog/full_catalog.pdf 

Hope this helps,
Robbie Jacob

 [ Parts orders are handled by the new owner:
 [
 [   Player Piano Parts, Inc.
 [   702 E. Second Street
 [   Wichita, KS 67202
 [   tel.: 1-316-263-3241
 [   http://www.player-piano-parts.com/ 
 [
 [ -- Robbie Rhodes (Ye Editor)