SP500 scanner auto color problem

[PHF]

I have SP500 scanner running stand alone with FE 3.0 software (from frontier 500). When i scan some films the auto white ballance is terrible. I need to take -15 yellows out and put +5 or +10 Cyan to make the picture looks good. Some films are perfect from the start. I can not find any reason. The films are old, 20+ years. When i make the correction - the colors are very good, the picture is not grainy and the colors are exactly the way they were on the paper picture printed in the past. Could this be the aging of the film or there is a menu where i can adjust such parameters? In the service meny there is a option for film channels and correction for each type but there is no data in this menu.

Any ideas ?