Rectangular chronograph pusher button 5.0mm x 2.0mm

Somehow I lost the SS pusher button on my 40’s Beleta chronograph 6B234 with Landeron movement.

The button is rectangular and slightly curved in parallel to the case, and 5.0 x 2.0mm. I’m not sure how long a stem. Perhaps I could have my watchmaker remove the existing one and take a pic.

I love this watch, so I am really willing to do what it takes to find a pusher button!