Thanks Rui, yes I like those alignment guides and will print myself 4.
I have found one of my Roller assemblies has split, for no reason I think than the print failed for a line. I was experimenting the concept of a little wipe of oil to lube the nozzle, but think I ended up contaminating everything. Thought it was only the outside, but when drilling the holes out, I found the whole layer had pretty much given up so my nice solid piece became two smaller nice solid pieces. Will reprint in PLA+
I tried to print a 25.4mm foot http://www.thingiverse.com/thing:1083038 from technomastermind as this was supposed to be for 25.4mm but I found it also too tight, as tight as the original feet I printed, so wandering if I need to re-calibrate my printer. Will print a quick calibration cube and check before I reprint the roller.