Quoted from jrebs:
Thanks for the input, explosiveegg. I'll investigate the jumping issue. My phone is a potato, but I have wondered if the ramp entry was maybe a little too steep initially anyway, so if I make some adjustment to smooth out the ramp entry it shouldn't hurt even if it doesn't solve it.
As for the back gate, that one is a real PITA to access. I haven't removed it yet because I wasn't sure what I'd be getting into with removing the ramps to get at it. I'll probably leave that for the last fix on the table and then pull that gate right out and give it a really good examination, cleaning and lubricating.
PS: Thanks also for the reference photos. I can use those to look for any marked difference in the gate shapes.
Make sure that little white plastic washer is there and on the correct side, otherwise the gate will shift.