[jakob]

I move my dob to the the top position until it hits the back vertical board on the base. I then measure the amount of out of square to the base and enter that figure into the Argo.
I my case:
setup alt ref/alt ref=+92.700 ( my end stop is past 90deg by 2.7 deg)

Now all I do, push the Tube to the stop and
mode fix alt ref/enter/enter/exit

I hope this will help.
Regards J.

ps.
You can use the Argo to give you this angle. Next time when you are aligned, set the argo to mode az alt, push the tube to the top stop and read the alt angle of the display!