My understanding is that all the rigid rams come apart in a similar fashion.
I would just remove the spindle and leave the quill in place.
This is how it was done on my BTC-1. My spindle wouldn't fall out so I had to use the block of wood and the hammer(shudder).
Remove the set screw that is on the back side of the bearing retainer and unscrew. Be very careful as the bearing retainer is cast iron. You must not hit it with a hammer(don't ask how I know).
The proper tool is a hook pin(pin hook) spanner?? I used 2 dowel pins that fit the retainer holes and a large pair of channel locks to grab the pins.
The next time I buy the right tool or I make something better.
Once the bearing retainer is unscrewed the spindle may drop so be careful.
I put a block of wood and some rags to catch the spindle in case it fell out.
I also cranked the knee up so the drop distance would be minimal.
If the spindle does not drop out you will need to use a block of wood and a hammer to kick it the rest of the way out. You could also rig a way to push it out as well. You need to put the block of wood on top of the spindle and hit downwards. Never even tap the bearing retainer!!!!!!!
On my machine I had to remove the stuff that does the tool holder removal so that the end of the spindle was exposed.
One thing to remember is that the bearing retainer is supposed to seat on the bearings outer race to hold them in place. It will not bottom out on the end of the quill. I believe that the factory spec ~.003 clearance between the quill and the bearing retainer when it is tight.
Mike
Warning: DIY CNC may cause extreme hair loss due to you pulling your hair out.