@SAT I've been using throttle swivels on some applications, mostly two stroke karts, where they fit in the throttle and are held captive by a snap ring. GEM 1358 comes to mind. Requires nimble fingers, but there are several versions out there.
I'm thinking Markus is probably aware of this, and looking for the original ones that were swagged in? Otherwise, the snap ring type would be a good substitute.
That is the Tilly swivel. They also sell a slightly larger one for Walbro that is probably more suitable?
https://out2win.com/catalog/images/LSWTSS.jpg And I forget how any of them stack up to the GEM 1358 (made for the KT 100) that I used on a Walbro on a Clinton two stroke!