how to make vintage keyboard works again?

[Idner7]

i got keyboard monterey k 108,vintage keyboard with alps skcm white.
its not working again,
when i open it,like nothing worng only switch a/x got rusty ..
how to repair it?
its posible for using new electrical part from new generation diy keyboard?
ic controler and some elecronical component then short it to pcb vintage keyboard?
sory for my bad english

[bamrocket]

Could you provide some photographs?
This might help us to diagnose your issue.