The 1910 Steinway-Welte upright piano would have been a Hamburg
Steinway fitted with a Welte-Mignon red roll player made in Freiburg.
No Welte instruments were manufactured in the USA prior to 1913.

Because Steinway signed agreements with Aeolian, to permit Aeolian
exclusive sales in the US for all Steinway pianos fitted with player
actions in 1910, we find that after that date only Aeolian products are
found in Steinway players in the USA.  Abroad, Steinway-Welte pianos
continued to be made with Hamburg-built pianos.  My own Steinway-Welte
grand was shipped to its first owner in Rome in December 1931.

As for finding the correct parts to replace the missing parts in the
gutted Steinway-Welte upright, I believe this would prove very difficult
indeed.  Much more available are Welte-Licensee parts which could be
modified to fit the piano.  They would be far from correct and would
limit the piano to Licensee rolls only, but would be a realistic goal.

Mark Reinhart