I need help with using the 41CL

[Uli]

I have nearly the same issue. Where is my mistake?
I have done the initial configuration from page 18 of the HP41CL manual, steps 1+2+3.
Afterwards I have typed:
alpha math alpha
xeq alpha plug1 alpha

I have tested the math modul with command sinh. It runs.

Afterwards I wanted to unplug the math modul with the command:
xeq alpha uplug1 alpha.

HP41CL shows : nonexistent.

I was not able to unplug the virtual math modul. It is still plugged in and I can see it in catalogue 2.

Does anybody knows how to unplug it?

Greetings