you want to make sure and not damage those rails as well. keep in mind those phillips screws are usually loctited in and they are a soft screw. you need a good fitting #3 phillips and be careful.
if the hyfax isnt too brittle and you have rail saving in mind, a sharp razor knife slicing the sides makes for quicker removal than pulling out through the track windows. sometimes hammering a chisel into the hyfax near the screw hole gets them moving rearward. from there, using the hammer again with a block of wood against the rail and hyfax until you can get a good grip on the end once it starts to exit the track window.
reverse the procedure for the install after you lightly sand and clean the rails with a scothbrite or emery. spray the new sliders with pledge along with the rails. they will easily slide up to the bend in the rails. from there, use a piece of the old hyfax to drive the new ones up, or your block of wood again.