DeLonghi Perfecta Cappuccino problem

Hello

First of all, please excuse me for writing in English, but German is not the best.
I have a DeLonghi Perfecta Cappuccino model ESAM5500.T
I bought it faulty and i want to restore it.
When i bought it, it had a faulty boiler and i thought that this is the only problem.
Soon i discovered that it has many more problems.
The brew group was completely blocked. I disassembled it and lubricated it, now it works fine.
I changed of course the boiler, i installed a new one.
Machine started and seems to work but still not OK.
When i switch it off, it does not stop in the correct position, it is a few millimeters lower and that's why i cannot remove the brew group.
I disassembled and lubricated the gear mechanism, checked the upper and lower microswitches and of course the brew unit drive spindle nut, which does not seem to have any play.
Interesting, that the gear mechanism seems to have a longitudinal play (the whole axle)
I solved this by using a very thin washer under the nut.
Things i tried to solve the problem:
A friend told me that this can be an issue caused by the defective usage of the gear mechanism, because of the blocked brewing unit, and maybe wrong values are stored by the machine. I tried a factory reset, and even reprogramming the PIC with a different firmware, which did not help.
I replaced the Hall sensor on the lower part of the gear unit. No change.
I tried to replace the brewing unit. Nothing changed...
I also replaced the brew group holder from a donor machine.

In test mode, both switches are working. My friend, who has a coffeemachine service says that he would solve this problem by changing the whole transmission mechanism, but i cannot afford that expense. I would love to solve it with minimal expense, because i already spent on the boiler.

Please advise.