The following error message occurs:
Error 3644 - illegal tool in position 1
The tool mounted in position T1 is not allowed in this position.
Position T1 can only carry "heavy duty" tooling like a Milling Unit or HD Unit. Make sure that the tool mounted in position T1 is one of the allowed tools.
This table, copied from the User Manual, shows the complete overview over possible tools per position:
There are no machine specific checks.