Prusa Mini failed on second layer - fixed  

Prusa Mini failed on second layer - fixed

After assembling the Prusa Mini+ the went well, but when I tried to print the Prusa logo file, the second layer failed. Almost no material was extruded. The extruder gear made noises.  I tried a lot of different things from the manual and from this forum. I cleaned the nozzle. Tried different temperatures and different spools (All PLA). But nothing helped. It seemd to purge material ok, and the first calibration layer was ok, but when the x/y speed increased on the second layer, not enough material was extruded. I tried increasing the pressure on the extruder, but then the filament got stuck in the extruder. 

So I hald to open the extruder block in order to remove the filament. It was not difficult. I just unscrewed all the screws on that side. What I discovered after removing the filament was that the groove in the extruder gear was not aligned with the filament. The ball bearing was not fully pressed into the orange wall. When I pushed in the ball bearing, and replaced the gear with the groove for the filament, it alligned fine.  After assemling it, the printer sucessfully printed the PRUSA logo. 

I have not seen this problem described, so I add it here so others can try it.