Einhell power file tensioner knob

The original part is a poor and bulky design imho, which doesn't lock into end position (as it is obviously supposed to) and wobbles around on the tool.

This design has a much lower profile and doesn't move on its own, and should install as-printed, without any extra parts. It features a positioning finger that locks into the body of the tool, and uses a printed spring to drive it.

Print in the orientation shown on the photo and in the .stl file, without supports. Problems may arise if your printer or filament sucks at bridiging.

Let the part cool well before installing - if it is still warm the plastic spring might lose tension. Before installing, press the positioning finger against a hard surface and verify that it is moving. If not, use a bit of force (gentle tap with a hammer or a squeeze with flat-jawed pliers), but it should work right off the build plate.