Hi, when I print something on my makerbot 2X it always bubbles at the Top.

Here is a Image of the Bubbling: https://postimg.org/image/cpy7e3vm3/

Here is a video of it making a item: https://www.youtube.com/watch?v=Ae4NjKFCE8w

Infomation: Filament Type: ABS
Printer: Makerbot 2X

I need someone to reply as soon as possible, I am showing my 3D printer at this place and I need to get this problem fixed by today because if i don't it will cost me a lot of money so please reply as soon as possible. Thank you!