Filament stops running smooth halfway

[ultifow 0]

Hi,

Sometimes i get problems with printing. Small objects he is doing fine but if i go larger and fill in the objects i get a problem that not enough filament comes out halfway during a print. I was busy to print Screwless Heart Gears from emmett. I already got the pins the inner core and the four small gears printed well. But at the four bigger gears not enough filament wont go through at some time.

I got the new upgrade of "the extruder drive" plus a new bowden of the latest version of the UM (which got a bit bigger inner diameter). It seems he get to much material around heater because filament is getting pushed back, moving back along the bearing wheel from the extruder drive. And then when there is a bit of space again, he pushes a little filament back in till it get pushed back again, and so on... (but everytime less material will come through)

When i push the filament back in with some force when the problem starts he let sometimes more filament coming through which lead into a nice, new, fine layer. But when i release it again not enough filament wont get through anymore.

After a few seconds i stopped printing and heater stays at 210 degrees (which im printing with) the filament is running through again but gets a bit blobby in mid-air because it had to much filament inside which came not through.

Got some tips or questions? Please reply them

Before u ask,

My bowden does not pop out,

the extruder drive works very well, the filament gets no ditch