Refitting the cross slide to can be a little tricky, I'm sure Myfords describe the correct procedure but I found that by engaging the cross feed knob, winding in the feedscrew until resistance is felt and then manipulating the leadscrew handwheel and cross feed together, the slide goes on without any problems. No force necessary, you can feel the feedscrew engage the key and then wind it in with the lead screw hand wheel. Place the gearbox in neutral or disengage the banjo for non gearbox machines.
Dave