I replaced a broken roller on my kitchen slide in the last year. With advice from this forum I used a hydraulic bottle jack and lumber cribbing outside to lift the slide within its frame one end at a time. This gave me enough clearance to get the new roller in (as I remember the old roller was missing), and add a new roller in a logical weight bearing part of the lower slide. I could take the old screws out with narrow nose vice grip pliers on the screw heads. I used hex head screws that I could get end wrenches on to secure the new rollers.
Of course, you have to disassemble the wooden trim on the lower front of the slide to access the weight bearing lower front slide lip.
I seem to remember the new J-38 roller frame being a little more solid than the old ones. I was sorely tempted to take the new roller assembly to a machine shop and have them fabricate a replacement out of hard steel instead of the thin roller frame supplied.