Hi Roy,
The pivot bushes are standard flanged IGUS Iglidur ones.
I've not got the spec to hand, but if you can measure them up, they are easily available online from igus.co.uk.
The mail seal between the slider and stanchion is just a wiper seal, so shouldn't be worn out.
I've never needed to look for one, but fits a 1.44"/36.6mm shaft, 0.2125"/5.34mm tall.
The difficult one (if you need it) is the main slider bearing. It's a 4" long DU split sleeve bearing that I'm not familiar with (AMP forks get through loads of tiny 8mm diameter ones

).
I don't think USE would have used a special bearing for this. There's no reason to make the shaft some weird custom diameter, and given that there's a wiper seal available for the same diameter, it must be something off the shelf.
View attachment 553672
All the best,