Jerry Peck
If the cast iron foot holds the weight of the tub, but is loose, try one of the strong, hard, two-part stick epoxies.
I would not rely on these epxoies to hold the weight of the cast iron tub as those tubs are very heavy, however, I think they should work when using them as a shim to make the leg fit tighter. Think of the epoxy as a moldable shim that you can force into the gaps between the leg and the tub socket where the epoxy shim will harden into what ever shape it is forced into.
