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My friend looked into converting it to ball bearings, but there
doesn't appear to be enough room. And one of the roller journals is
made with a taper. We assume that the taper is there to handle
thrust in the machine.
Any chance the taper is just "wear"? Maybe good needle bearings
would work instead of ball bearings - although the bearing bronze
mentioned below would probably give you long enough life provided
sufficient lube was available.
Ken.

The bearing system is unique, at least to me. There is only one
"half shell" type bearing on each journal. This is on the side that
takes the pressure from squeezing the cane. The block that retains
the bearing is similar to an automotive crankshaft bearing cap. But
instead of being about an inch or so thick, it is about 5" thick.
And the diameter that holds the bearing shell is recessed down into
this holder block. A lip of material then retains the shell and
prevents it from turning.

None of the original bearing material is left. Any idea what the
preferred bearing material would be for this application? I am
assuming that a bearing bronze would be the choice for this
application. This is a low speed, high pressure application

John