Locating replacement part - Truth

I am having difficulty locating a replacement part for my casement window hinge. (Part of the stem on the crank broke off.) Photos of the broken unit is attached.

IMPRINTS on UNIT:
crank base, underside: US PAT. 4,241,541
crank base, top side: 12 03
9.5" arm, top side: EntryGard Truth
9.5" arm, underside: 40754
2-part arm, first part (attached to a gear), top side: R
2-part arm, ffirst part (attached to a gear), underside: 31538A
2-part arm, second part, measures approx. 3 13/16" (no imprint)

Your help is much appreciated!

Pamela