how to disable bed and bath door knob from 60's
i bought a house this summer that was built in 1963. the door knobs look like they are original. they work fine. all the bed and bath knobs have a slot on the outside and a tab for twisting when locking the door. i can not twist any of the locking mechanism. either with the twist tab or screw driver in the slot. i took the knob off. much of the mechanism inside is encased. all i can see are the parts that go between both sides of the door. i have found no manufacturer name. the house is still pretty much early 60's vintage and i would like to keep these door knobs. is there a way to have these work so that they can be lock when desired?
i have a follow on question if this can be resolved. and that is how to clean 50 years of hand scum off the knobs?
thanks for any help.