Replacement hand cranks

Hello there. This looks like a very old operator design, so I am honestly not sure if we'll be able to help. The spline diameter looks possibly close to 11/32", but pictures of measuring tape aren't always immune to depth perception error, so please double and triple-check this for yourself. If so, however, a handle like our 39-114L might work for this setup. Take a look and see what you think.

Alternate view of the gear hole