Collected repaired shock absorber from Les at Steve Price’s today.  Fantastic job.  Les welded up the casing, fitted new bushes and seals and repaired the broken internal operating lever.  He also explained how to dismantle the rest of them, should they need doing:  pop out the rear core plug, remove the seal and press the shaft out from behind.   I have the old bushes so I can measure them for OD and nominal ID.  However there is no play and plenty of resistance in the other rear shocker so will leave that alone for the time being.