<Do not pass go, do not collect 200 pounds>
So. Adjustment plates produced by laser and returned nicely, tapped OK in the laser hole but had to try 3 M4 Taps to find one that worked well. Adjustment plates assembled and fitted on one side, was getting ready to fit the other side when the movement of the gantry got my attention.

Several months ago I applied some light machine oil (3-in-1 I think) to the hiwin rails and ran the gantry on the X Axis back and forth a few times, was satisfied with that and thought nothing of it. Fast forward a couple of weeks and the oil had dried into an almost varnish like residue that was possible to remove with a scriber but left a glue like substance behind. Bottom line the oil had gummed up the rails and the linear bearings were not so much cutting through it as riding roughly over it. The gantry had become still to move and it didn’t feel smooth at all. So took one rail off today, checked the bearing block and it seemed OK. I spent about some time with light sanding paper on the frame where the rail has been bolted as there was a rim of hardened oil residue all around the rail, that done I took a wire brush to the back of the hiwin rail to remove the frame residue that was stuck there and then thoroughly cleaned the rest of the rail with degreasant and elbow grease. The rail came out really clean, the bearing I had removed ran rock solid and smooth over the rail and once bolted back in the gantry is noticeably smoother. I'll do the other side next day or so. I have already got the right type of grease for future lubrication but thought I'd post this as a warning to others of what not to do. Once that's done I'll work on the alignment of the second X Axis screw and bearings and then go back into Mach, check the connections, limits & homing and finish setting the soft limits which is as far as I got before I took several steps backwards.