The song-1-memory slot had been occupied indeed, but I already had it cleared. And still... BUT: The decisive hint was to start the recording of the rhythm part with pressing the SYNCHRO button, and not the START button, which I did! Sorry I missed this idea. But man, it works! Thank you all for your efforts and help, and many thanks, Ted, for saving me from playing just a triangle... ;-) Great! Best greetings from Hattingen, Germany!