extruding problem

Hello everybody, i've just build a mendel prusa and i'm having some problems.

I was printing a test piece, to valuate the printing setup. Then the PLA ended during the extrusion.
So i stoped the extrusion, put more PLA and sinse that, the machine is not extruding anymore. I will explain, when i put the plastic and say the machine to extrude, it starts to pull the plastic, but in a certain moment the motor continue to rotate but the plastic stay stuck.

Can anyone help me?

Thanks a lot.

What hotend are you using?

Has this one in the pic...

I discovered what happened, when i was extruding the PLA finished a piece of PLA gets stucked between the screw and the hot end..... It was interrupting the alimentation....

But now i have a bigger problem.... when i was assembling the extruder back, i realized that the other screw (the one thats the PLA pass inside) don't assemble with the black plastic part anymore.... i don't know why...

So, trying to assemble it back i broke the hot and as you can see in the picture and also broke the thermistor too./.

thanks