SELINA THE WALKING AND SINGING DOLL

I've could colletc some information about this doll, its from the Zapf Creations Factory, my father bought her for me in 1975 in Germany. She has a japanese mechanism that aloud her to walk, sing and talk. She still has a disc that goes in the back. Originally I believe she had 4 discs. Unfortunately the mechanism it's damage and I couln't find someone to fix it. She has60 cm tall, the dress and shoes are original it's in good shape.
I would like to know her value more for curious reasons. Thank you