Ender 3 filament guide and runout sensor

This is a little tweak to the (almost) perfect [Ender 3 Filament runout sensor and guide with bearing](https://www.thingiverse.com/thing:3357097) made by [blaiseb](https://www.thingiverse.com/blaiseb/about).

I love the way the guide is just plugged onto the printer, but unfortunately I had the problem that the back of the guide was lifting up over time because of the tension of the filament. Also the space between the bearing (608) and the switch (KW12-3 microswitch) I used was very narrow,