I have removed both the anchor and adjustment fasteners from the ends of the door, however the roller acts as if there is another (fastener) anchor possibly on the top of glass edge that prevents removal of the roller assembly? It also appears that the dust seal slots may also interfere with roller removal as they encroach into the opening but I think I could machine off to allow access if needed. I have pried on the roller assembly w/o any fasteners and it seems quite fixed so I cautiously stopped before I broke it.
The roller unit appears to be diecast and wheel pivots for height adj. I'd estimate the wheel to be about ~1-1/8" dia. As a Mechanical Engineer this is quite surprising to me to be unable to remove roller assembly and hoping there may be some "trick" short of total door disassembly for replacement.
Thank you for your time and your guidance is eagerly awaited! I believe the door was made by Alenco in Bryan TX (photo above) who is now out of business in that location.