My fairly new Mu Uno only has about 500 miles on it, but some of those were under wet, muddy, touring conditions, as recently posted here.
I've only folded it and unfolded it about ten times, but I had noticed before the tour that it was hard to get the frame to fold after opening the clamp. In hindsight, that should have caused me to double-check the adjustment of the clamp, but I didn't.
Anyway, at the end of my tour I actually had to kick the frame a bit so that it would fold, and as I feared not only had some dirt and grit found its way in, but the mating surfaces show wear and a plastic piece is damaged. (Likely due to my forceful folding -- I'm not proud of that, but I was in a hurry to get it ready for transport at the end of the tour.)
I've never serviced one of these hinges before, and other than the instructions for adjusting the tension, it isn't clear to me how to which parts should be lubricated, if there's a best type of lubricant, if I should be worried about the wear on the frame and, most pressing, if its possible to get a replacement for the damaged plastic piece.
Here's a photo showing the damaged plastic piece (from what I can tell it just prevents the clamping bolt from swinging around, so I bet I can make due if replacements aren't available):
Here's a photo showing the worst of the wear on the frame:
And, finally, in case it's not clear what's what, here's a picture showing the entire hinge area (from here one can see that the plastic piece has actually been pulled away from the two bolts intended to hold it in place, thus stretching, thinning and warping the plastic):
Any tips / advice would be much appreciated!