Lexus RX330 '04 6-disc CD changer: spinning CD mechanizm?

Lexus RX330 '04 has 6-disc CD changer part 86120-0E019. My wife put in there CDs with applied labels - changer shows Error 4 constantly. On internet and in Lexus dealership everybody says: only replacement. I bought the same part from some scrap yard - here are things with this unit:
1- it is spinning an empty CD mechanizm for about 30 minutes after it is turned on and after it is turned down;
2- showing only CD 1, 2, 3 and 4 - but not 5 and 6;
3- does not accept a CD to be inserted;
4- the least significant problem - it is not exactly fitting.
A suspect that either it is in "shipment mode" and I have to change the mode to normal, but I can't find how. Or the unit is damaged. Or I need to do something else to re-set either the unit or the computer which controls the CD changer.
Any suggestions?