We can't really help you with any specific vendors that you couldn't find yourself with some internet sleuthing, but one way you can solve this is to find a machinist or metalworker in your area that can repair or recreate suitable parts for you.
What you show is just a worm-gear arrangement of some kind. Depending on the damage, such parts can often be rebuilt or scratch-built quite easily with modern metalworking tools.
This is definitely a case of trading your time (searching for and acquiring parts) for money (paying a tradesperson).
You may be able to find a metalworker in your area with some web search terms or by asking your local union or "maker space". YouTube is, surprisingly, an excellent way to find local tradespeople who might be interested in an easy fix-it project in return for an opportunity for a bite-sized project for a video.
Of course, in a pinch you could contact Steton directly. Even if they can't sell you new-old-stock parts, they can probably provide part names and numbers and perhaps manuals that you can use when talking to a machinist.
It does appear that this model is a "panel saw" so you might have better luck with those search terms.