Howto for Password Reset for Kicksecure Root Account

Helo,
Kicksecure is installed on a rather old MAC.
User- and Root (Sysmaint-) account have different passwords for login.
I don’t know why but anyhow the password for sysmaint seems to be wrong, so I can’t login. Access for user is still ok.
Obviously editing Recovery Mode like in other distros is no longer possible as a precondition to set a new password.
Is there another rather simple, direct way to reset the sysmaint password and set a new one?
Thanks for help in advance.

Recovery mode can be used. Documented here:
Recovery Mode