First, check the fixing screws for the cross slide nut are tight, then turn the handle back, to the point where the slide starts to move, then forward to the point where it starts to move again and note the readings on the dials, to see how much backlash you have. All lathe feed screws have some backlash, if there was none they would not work! You operate the lathe by moving the tool up to the work, just touching it onto the work, then zeroing the dial on the handwheel and working forward only from that point, thus eliminating the backlash. Backlash is not neccasarily wear, it is common to all threads, if you have too much of it, you can replace the thread and the nut. How much is there?
Phil