I got the bearings off the spindle - this way....
Remove the locknut and washer, place splines in lathe chuck with packers to protect, get blow lamp, run lathe at low speed, aim heat at inner race-the spinning shaft ensures even heating. After a few minutes the bearing just slides off with a gentle start from a rubber hammer, rinse and repeat for each bearing but make sure to allow the shaft to fully cool between each cycle.
The bearings appear to be in good shape and i will refit them if only just to see if it works. I cleaned in a three-bath wash of white spirit going from dirty to clean then dried-off with paper towel and soaked in spindle oil (these will be going back with oil not grease), they feel slick and very smooth so i see no reason not to refit.
If it grinds itself to bits in a day then now i know how easy to change them it will only mean minimal down-time.
I have a feeling the hard part is going to be getting the spindle out of the quill - pretty certain I fitted a longer screw to hold the Z axis drive which will block removal of the spindle assembly. If that is the case it means stripping the Z drive down which is a bigger PITA.