One thing I can add from experience is to resist the temptation to add pressure with the tire jack when that new mast step doesn't seem to seat itself just right on the crossbar.
Mine popped right off and I had to rethread the mast step. I also had to flatten the top of the crossbar to get the new step on because the striker post had bent a lip around the hole.
Mine wasn't very corroded, probably because I sail in fresh water. I'm learning from experience, and I haven't had the severe corrosion experience yet.