So I ended up changing all the rollers with the mast still on the machine. But I did as you said and removed the stops, and chains( one section at a time) and was able to replace the rollers when each section was dropped below standard height about 6".
I started out with the front of the machine raised up on blocks about 8".
After replacing all 12 rollers this time I feel like it will go a lot faster if I ever have to do it again.
I did make a special lifting bar for the third section as there was no way to put a strap around the top like the first two.