Brother HS-3600 – Error 322 (Servo deviation Y) and how to access service/test mode

Hi everyone,
I own two Brother HS-3600 wire EDM machines. One is working perfectly, the other one is currently under testing and giving me a persistent issue I can’t solve.
? Problem:

During Y-axis planar movement, the machine triggers the following alarm:

Error 322 – Servo deviation Y

Normal manual movements on both X and Y axes work fine, but as soon as the Y-axis tries to maintain position during a program or slow move, the alarm pops up.
???? Troubleshooting already done:

Cleaned and lubricated guides and screws

Replaced Y-axis motor

Replaced linear scale

Replaced XY servo control board

Calibrated VR4 and VR10 potentiometers on the PCB

Checked all voltages (everything OK)

???? Software status:

Performed full panel reset (XY etc.) – no effect

I can access the <SPECIAL> screen, but it only shows I/O output tests (valves, motors, relays).

No access to <MANUT>, <GAINS>, <SERVO> or any tuning menus.

Codes like 999, 1111, 3737, 2002, 0724 are rejected with a beep.

I’d like to also back up the working machine’s parameters and write them to the faulty one.

? My questions:

Is there a key combination at startup to enter test/service mode?

Is there a way to adjust Y-axis servo deviation tolerance or open the full servo tuning screen?

Can anyone confirm how to safely back up full machine data (via floppy or RS-232)?

Has anyone here successfully unlocked hidden menus or updated firmware on a Brother HS-3600?

Any help, hints, or documentation would be very much appreciated. Thanks in advance!

Best regards,