When starting a new print with the same filament, very often the filament will not extrude normally. To avoid this, the best I have found up to now is to make a systematic Material Change before each new print. Then when the filament comes out of the entrance hole, I have to cut by a few millimeters the tip of the filament, and then continue with the normal Material Change procedure.
This procedure works OK, but of course I would prefer to be able to make several consecutive prints without the need of making it.
It seems that the problem arises because the tip of the filament has a diameter too large to enter the noozle when I do not make this cut.
If anyone has encountered this problem, and solved it, please let me know.
I am typically using PLA filament, with the right 2.85 mm diameter.