I've got Filamentarno Flex filament. It is amazing to print flexible parts with no speed down by the way. And of course it is failed to extrude in stock.
I've printed the source, but it failed too - the filament runs into space between the part and a wheel. So I've reduced that space as much as it possible.
So if you does not success with other options, try this one.
It is not ready right after printing!, so a knife is your friend to fine tune. The gear should rotates without any obstacles. Check it with filament feeding tools in a printer menu. See the image
speed 40 mm/s, flow 110%, cooling 80%, retract 4mm