Problem with Y-axis Maho mh 600c

I´m trying to help a friend with his MH600C, the problem is that the y-axis is not reset to zero when he turns on the machine. The Y-axis just keep on sinking.
There are two lamps that is glowing on the Indramat program module, se the uploaded picture. We have changed the Indramat module without any result. Is there anyone that have any idea on this and maybee someone has an service manual for this machine.
Regards Per

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