[mactec54]

Thanks for all the great suggestions and now I feel I I definitely have more options regarding the rust removal but maybe I should have phrased my question better because a large concern was perhaps the existence in question no longer running true due to w had uneven fit...or slop in bearings...should I not worry about this? Cutting soft metals with this machine prior to the rust was already a task in itself

It would have to be very badly rusted to have any effect on the accuracy of the rail, the bearings run in 4 straight lines, so if there was an affected area then you could rotate the rails to give you an unaffected area, keep some protection on them if not using, even just a wipe with a oily cloth is enough