Does anyone have any knowledge on FOER5.2s steering system?

Ours has started to bind and become almost undriveable without weight on the forks. It appears to be binding in the column rather than the steering box, but can't be certain. I've flushed out the box with clean gear oil(?) and wasn't any debris, although what came out was almost grease like.
We have a spare dead FOER5.2 truck with good steering. I'm wondering if there is a replaceable bearing in the column or alternatively is the column easy enough to swap out, with the 4 bolts at the base where it joins the box? or would it be better to just swap out the whole steering box and column?

Any help is much appreciated.