Hey Doug,
I can't speak for everyone who uses them, but I usually put a drop of lube in both ends of the grip a couple of times a week. Haven't had any troubles. You could try emailing Inkjecta or Protat. They're pretty good with correspondence.
As for the bars, I like the 4mm cam with the soft bar for lining, 3.5 with med or hard bar for just about everything else and the 3mm with the rigid bar (I bought that separately from protat) for black and grey. I've had mine for a couple of months and am still trying different combinations with different applications. It's really a pretty amazing machine. I hope that helps a bit.