With the cross feed nut being loose, it encourages you to be careful in a way that will serve you well in all machining tasks. It can be used -if used carefully - until the bronze nut is almost gone. I've used a machine with .080 slop in the cross feed and did reasonable work on it.
Nice thing about cross feed screws: they are all very similar in design. as long as you get a matching nut and screw, and the diameter of the thrust bearing and screw are close, a very nice replacement can be accomplished, even if it means shortening the screw, or making a bushing for the rear contact, etc.