Z-Glass nightmare

I just upgraded my v4 printer to the v2 hotend to be able to use z-glass as I've been trying to print large models with ABS or Ultrat without warping to no avail. I have side panels and even a top cover. 

After upgrading the hotend and recalibrating the platform level I tried printing with Z-glass for the first time and the extruder motor started skipping and the print failed during the raft. Not enough material was pushed out. 

I switched to ABS and at first it started skipping, but after the fist layer it went back to normal and finished printing a test part with ABS. 

I just spent $100+ on the hotend and Z-glass, is that normal? How can I print ABS but Z-glass failed miserably? Z-glass is brand new, hotend was brand new, platform was leveled properly. What can I do besides send it all back and ask for refund? 

There are many reasons why the extruder motor skips. here are a few I know off

1: the screw that holds the bearing against the extruder motor worn or bent.

2: the extruder gear worn

3: dirt or leftover filament from last unload still in extruder

4: heater/sensor screws not tight

5: Clogged or damaged Tip

6: ribbon cable failure (usually not heating properly)

7: the bearing against the extruder failed (this will be a failure for all filaments) 

I have issues like you describe on HIPS often where only part of the raft prints, I used to dismantle and clean everything and clean it but I have found that I can unload the filament, trim a couple of inches (50mm) of the end and reload, when it is reloading I push the filament in by hand adding a little extra force to feed the filament and some times I press load a second time and make sure the filament is flowing smoothly, then I start my print again, usually works.

Did your hotend came with nozzle mounted on it or you still using 'old' one?

Marcin, it's a brand new hotend, so brand new nozzle as well. I spent a lot of time making sure there was nothing stuck in the channel from the extruder to the hotend, it's clean all the way. Extruder gear looks new, I don't have that many hours on my printer and even checked the gear screw, looks good to me, but it's hard to know for sure. 

Anyway to eliminate some of those possible failures on cable, etc, I printed with ABS without issue, so I know the printer is working and the problem is the material. 

ok, looks like hotend and z-glass are going back. 

My problem with Z-glass are extreme stringing.

When i load Z-GLASS or HIPS i choose to load the filament two times to really flush out previous material from the nozzle.