Looking for Diavert Phase Ring

[Allison Haggarty]

I am looking for a phase ring for an old Leitz Diavert inverted microscope
(bought in Canada in the 1908's).  The original part number was either
520381 (in manual) or 25203810 (on our invoice).  The ring has "Phaco 1"
marked on the handle. Any help would be appreciated.