Wurlitzer 1650a

Good morning from Italy, i ready buy a Wurlitzer 1650 A, after some week of restore the jukebox wornking bur necer stop to selection a records, all selection are reset , i see that a swicth on "bank selection" that is control about a fork inside of bank never move and so remain always close so a jukebox believe that trere are other selection.
With mechanical parts nee to move a fork because in service manual i don't find.
I think that this part is oxidized or rust, If you know a solution please let me know and if is possible also a photo of particolar, maurizio.capovani@telecomitalia.it.
Kind regards,Maurizio