HP DesignJet Z5600 - Error 21:13 (0x 10901002)(....ControlledMotorWrapper/ServoMotor....)

[RolEck]

Hello,

we (Customer) have an issue with one of your HP DesignJet z5600 plotters. I have tried restarting it several times, but the behavior does not change. There are no visible obstructions (such as paper scraps). The carriage can be moved freely when switched off.

Description:
-When the power supply is switched on, the plotter starts up.  However, at approximately 80%, it always displays the following error message.

21:13
Error Code 0x 10901002

Description: unavailable
File: ps-threadx-opt/elekra/hal/motors/ControlledMotorWrapper/ServoMotor/ServiceServoMotor.c
Line number: 1012

This message suggests that there may be an issue with the servo motor?  Unfortunately, it seems that our service provider does not have a replacement service station available

Question:
1.) What are common causes of the error?

2.) What can definitely be concluded from this error message, and what cannot?
3.) What else can I check?

The error matches the description here almost exactly: https://h30434.www3.hp.com/t5/Printers-Archive-Read-Only/21-13-Error-code-0x-10901002/m-p/8308431

What I don't understand:

As soon as I switch on the rear power switch, the plotter starts up and then displays an error message. I can't press anything on the plotter. except expand the error message. I can't interrupt anything, 

In the manual linked under the link there is the following:

"Entering the Diagnostics Menu
1. Make sure the product is switched off with the Power key on the side of the Touch Screen Panel, and not with the power switch on the back of the product.

There's an illuminated power button to the left of the touchpad, but no "power key(?)" on the side of the touchpad itself. I can't press or deactivate the power button because the device starts automatically as soon as I flip the power switch.  I can't access the diagnostic menu, which probably wouldn't help me anyway.

My only hope is to try cleaning it again, especially before Christmas. But I'd have to go through the 580 pages of the service manual to figure out what's relevant. I could take apart small parts myself; removing a cover is no problem.

Greetings and Happy Holiday.

[Repairatrooper]

21 ERRORS in most cases are going to be caused by either a jammed service station or a dead one. If there are no obvious cause of jam, just replace the service station.

https://www.lpscomputer.com/products/hp-designjet-z5600-service-station-t0b51-67023?srsltid=AfmBOopu...