I once saw a Triumph disc playing musical box that played Regina discs.
While the tuning of the combs is the same (or I should say that the
relative tuning) between several disc playing musical boxes, the
differences show up just as you have mentioned -- the center spindle
and the drive gear.

In the Triumph, someone took out the original parts and replaced them
with Regina-type parts so as to be able to play more readily available
discs on their machine.  As Triumphs are very rare and Reginas
extremely common, if they didn't have a large supply of Triumph discs,
and they are unconcerned with originality, I can understand why they
would do such a thing.  (Please don't assume that I condone it!).

I would recommend replacing the drive gear and spindle with an original
or reproduction Olympia gear and spindle to return the machine to its
original glory.

Eliyahu Shahar