Bad print quality and shrinking in z axis


I'm wondeing if this happened to anyone here before, and if there's a solution to avoid this problem. To begin with, the issue started recently. If you take a look at the pictures, you can see the really bad print quality of the prints. Also, it seems like the nozzle is pushing the platic too low on the print, pushing the previous layer down and shrinking the print in the z direction. The platform maintenance and calibration are already done but it does not seem to prevent the problem. The grey prints are ABS and the white ones are Ultra-T.

Any clues?

Thanks a lot!

Sounds like extruder could be bit sunken. I would suggest you taking full [url=]Axes maintenance[/url], including [url=]Jig Method[/url]. 

ps. pay special attention to axes block covers (pic attached), make sure that guides are stable and blocks itself arent broken. 


Will do!