Extruder Idler - Extended Guidance System!

Has anyone of you ever experienced the filament to move away from the gear wheel and loose a print for such a stupid thing?
I found out that especially with slippery and flexible filaments like nylon this can happen as no matter how much you tighten the screws of the extruder idler the filament just departs the gear wheel to one side or the other and the printer stops extruding.

I redesigned the whole extruder idler from zero as I only had an STL file of it.
The new one is made in two parts