I know this is an old thread, but I had a very similar thing happen to me over the weekend. Same tractor (new Kioti CX2510 with cab). I took delivery of it last week. I put a GWT quick hitch on it. I had a 500lb flail mower on the quick hitch and was getting everything adjusted. I was raising the 3PH from the rear position control lever and not paying close enough attention. The 3PH rose a lot faster than I expected, almost pinning my hand between the quick hitch and the rear position control lever. I moved my hand out of the way (no injury, but certainly too close for comfort) but somehow the 3PH rose enough to contact the position control. Quick hitch was also up against the taillights (but didn't crack them), and the top link was against the metal plate that holds the SMV placard (which wasn't installed). I don't know if the 3PH stopped because it finally reached its upward limit, or if it was binding on something.
As the OP found out, I wasn't able to lower the 3PH because the QH against the rear lever kept the "main" position control lever from moving. Fortunately, I was able to lengthen the top link enough to get a little distance between the QH and the rear lever, and that allowed me to lower the 3PH from the inside lever.
I figured something had to be wrong with the way the tractor was set up. My JD 4110 (similar size tractor, a little smaller) had a QH on it, and it's never come close to raising high enough to contact the tractor. I also didn't want to worry about having to closely watch for this happen every time I raised the 3PH. I looked into buying the little knob that limits downward travel by physically restricting how far forward the lever can be pushed.
My top link was mounted in the bottom hole (of three) when this happened. I think it was delivered that way, but not sure. I moved the top link to the top hole, adjusted the top link for the flail mower, and tried again. This time, I was able to raise the 3PH to its limit without the QH or top link hitting anything.
I'm still liking the idea of adding a second 3PH travel limiter to be able to easily set the upward travel limit for the 3PH. It only costs about $10, and I think it would be good to set an upward limit on the 3PH (when using a flail mower) to limit the upward movement when raising the mower to turn around.