Leaking plumbing in 1929 house?

hi well it's most likely that the overflow gasket is leaking you can replaced this pretty easy remove the screw or screws from over flow plate, then push gently that will loosen the overflow pipe behind , you can buy a replacement gasket at any plumbing store , put in thru the hole then put the screws back as you tighten the gasket will expand behind it , also you can put silicone around tub hole and gasket that can also work good luck !