Keeping on Please read my previous message carefully as I said: I tried twice maybe three times only to get a ticket or even a 0.99EURO/Minute charging over the phone... Just to mention the problems I am facing ... Problems I did not create...
Maybe there are some more than you think and JUST did not have the time with the ghost chasing... And I mean that I had to contact so many times take a ticket, without a straight answer, THEN waiting another week to get another nosense answer,
Well you see I bought the printer because it had ALUMINUM BLOCKS and thick bars ... And the machine was meant to print REAL PROTOTYPES.... NOT THE STARWARS FIGURES. Not That I do not like STARWARS but I wanted the CRAP PRINTER to PRINT some descent work and being able to keep on with my creations and DEADLINES!!!!

I will not say the printer is perfekt but for a Printer who is already more than 10 years old he is still useable today ( there are only a few update over the years like dd3 / alluminium parts ..)

ANSWER:
The PRINTER IS WAAAAAYYYYYYYYYY LONG TO JUST THINK IS WORKING................ NOT PERFECT HAHAHA...

you buy a DIY but not get it working , but reworked by yourself a lot like it looks like less knowing about it ( sorry why should someone try to use a nema 23 for Z if its already soo much force necessary to move it)

ANSWER:
OK!!!/// Now we are talking THANK YOU FOR THE QUESTION...
First the Steel plate is too heavy for the NEMA17 to move . Imagine when you have a part of 400x400x350 (mm) as the nominal printing capacity HAHAHAHA...

Then the 3 Bolts for moving the Z-AXIS are not balanced since the movement comes from below and when the heavy steel plate is on the top the bolts just loose their balance.. You can see with eye ...not instruments that bolts-axis are way out of linearity . THUS INCREASE THE TORQUE NEEDED.
THIS IS NOT MY FAULT IN ASSEMBLY...

Then the POM material is WRONG MACHINED POM (POM=Plastic black material for the Roll bearings... The base of roll bearings) for the rest who might read this.