Mine did a similar thing on the up and down, not the curl. It was ice in the detent thingy. Look on bottom of the joystick. There should be two large hex things, 1-3" long. Unscrew them (no oil will come out) and look inside. If you see rusty colored junk in one, that is the one with condensation inside, which freezes. Dealer told me to drill a 1/16" hole in bottom for water to run out. I did that, warmed it up, sprayed carb cleaner in there, then compressed air (repeat several times) to get out the water polluted grease, sprayed aerosol lithium grease in there, and voila! No prollems since, even in -18F temps. Might be your prollem.