first of all: i have to choose on Star to write something here. Okay, one Star, because the writing here is possible.
I purchased a B1-SE-PLUS-Printer and the Dual-Z-Upgrade in one Order at the same Time.
I got the Printer first and have to wait for the next 14 Days to receive the Dual-Z-Upgrade.
Once mounted the upgrade-stepper humms only an the original-stepper goes his own way, bending the Boom.
I contacted the support three times, they respond only on the chinese-trader-way.
They took my money and thats it. Beware.