Ed,  The oft-overlooked Player Piano Company has what you require as a
regular catalogue item.  Sprockets for Ladder Chain (42 links per ft.):

Stock # 1260 - 12 tooth  $4.75
        1261 - 14 tooth  $4.00
        1262 - 16 tooth  $3.25

Prices may have changed slightly.  More sizes may be available but
a new catalogue has not been printed since 1995, so just ask.

There may be many other sources for some player piano supplies, but
only Durrell has the stock of even the most obscure parts.  I truly
hate to think where we will all be if he ever closes up shop!

Yours in automatic music

Ken Vinen - Canada.
A PPCo customer of forty years