Hi, all. Been off the forum for a while.
Both of my cars had this issue, as does a friend's i-MiEV. Like others have said, the fix for this is to lubricate the lever coming out of the gearbox that connects to the shifter linkage. Since this is all open to the elements, the bearings dry out over time and cause stiff shifting.
For my cars, I simply used a few drops of engine oil and worked the shifter to loosen everything. With the car on a flat, level surface, apply the parking brake, put a couple drops of oil on the shifter rod coming out of the gearbox as close as you can to the bearing seal on the gearbox, a couple drops in between the black plastic box and the arm, and a drop where the shifter cable attaches to the arm. Then, in the car, apply the foot brake, turn the key to either Accessory or On (don't start the car), and run the shifter end to end several times. You should immediately feel the linkage loosen up. Put the car back in Park, put one more drop of oil in these three locations, then run the shifter from Park to B (or C) and back a few more times. Shifting should be back to normal.
The shifter arm on the gearbox can be accessed pretty easily with the car on the ground.
"Bear" - 2012 Diamond White Pearl ES with QC - 2/21/2013
"Koorz" - 2012 Cool Silver Metallic ES with QC - 1/5/2015
"Photon" - 2017 Bolt EV LT in Orange with QC - 7/31/2017
Solar-powered since 10/10/2013