The original filament sensor, which uses two bearings, does not prevent the filament from moving vertically and getting stuck because of it.
This design moves the filament through a tube, which should reduce the number of jams.

It is bolt on solution, but you still need to buy 5.5 mm steel ball (used in klicky-00) and 2x10 self tapping screws. You also need to resolder the switch from NO to NC; to do this, simply resolder the red wire to the middle pin. You have to drill a 2 mm hole through filament pass. The ball should move freely, so some sanding should be needed.

The version for the 4mm PTFE tube is currently unprinted and untested (i am not sure it 4 mm tube fits). To use the 4 mm tube, you'll need to reprint the buffer body or drill a 4 mm hole in it.