Most Victor player parts are available from Duane Wyatt at Wyatt's
Musical Americana in California.  He has a huge inventory, and probably
could have supplied the winding gear shaft.

However, the proper reproducer (head) for the Credenza is an
"Orthophonic" head, which is very rare (due to its having been
made of especially nefarious pot metal) and very expensive (due to
its complexity).

Wyatt may be able to help you, another source is Bob Waltrip in
Levelland, TX.  Be aware that these items will run minimally $200.

> I would like to find a motor and turn table, tone arm, etc. ...

Wyatt's.

A. B. Bonds