Filament loads but won't print

It could be a couple of things. 

One of the more common issues though is the print bed may not be leveled accurately.  If the nozzle is too close to the printing bed it may not come out at all or correctly.  I had a very similar issue to what you are reporting when I first got my printer.  The print bed was uneven thus allowing the test line to print but nothing else.

I would use the guide Carl developed to level the bed using the paper method.  The built in leveling does not work so great.  You can find the guide here:

http://www.soliforum.com/topic/8408/bed … beginners/

Thanks for the credit, but I simply shared it. This was the method used for years before machines started having built in automatic processes. So I can't really take credit for the development.

I would think if you have filament loaded and used the load feature it would extrude additional filament.  I would perhaps try to unload it then reload it with a clean cut end.  One other issue I recall when I first started is that I was not getting the filament properly loaded and in far enough.  This does not sound like your issue though since you were able to extrude some filament.

Did you try the bed leveling approach per my prior response?

I would put a lot of money on the nozzle being too close to the bed.
That can cause back pressure in the heat tube and the tip of the filament swells preventing it extruding till you pull it out and reload.
If so, turn all the thumb screws a quarter turn to the right until you get it printing.