well awesome job if you did accomplish that while it was still on the machine.
either way, on or off the machine it is still rather tedious doing that.
Those masts were always troublesome to deal with but i'm glad you got it done. (yep those clearances are tight in those for sure).
i mentioned that it may have been a cascade mast but i think they were bought out by another company, i think they changed the name to Lift-Tek or something like that. I think cascade is still the parent company but they developed a new division called Lift Technologies i think. In either case the new masts will be tagged Lift-Tek i'm pretty sure.
When it comes to the high lift masts that are 4 or 5 channels these guys are the ones that make them i'm pretty sure.
anywho, glad you got it done (without injury) ;o)

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.

the mast will have to be removed and laid down on the floor.
then the mast chains taken loose and cylinders removed
then you should be able to move the channels up and down to gain clearance on either end to expose the rollers.
There might be stop blocks on the top or bottom that might restrict the mast from moving the way you want it to. If it is a cascade mast then those stop blocks are usually removable.
Once you get these items out of the way the channels should move so you can get access to the rollers.
I do want to make it VERY CLEAR, be very careful when dealing with these and always mind your hands while manipulating the channels, use pry bars if needed. This kind of work is tedious and sort of dangerous. You get your hands or fingers in the wrong place while moving the channels you could pinch and hurt yourself.