First thing to inspect are the shifter cable bushings on the transmission side. The bushings will have premature wear on the center and will wear oblong. With the bushings being ok, then check the other end at the shifter base.

 

Thanks! Did so and couldn't see any problems. Ended up buying used shifter assembly and had it installed by dealer. Tech wasn't told details of problem, just that customer wanted assembly replaced. Tech told me later he test drove before install and didn't notice any problem but installed other one as per instructions. Said sometimes a stone or other object gets lodged in the area where cable connects to transmission linkage and that can block shifter movement. Anyway, he didn't inspect it so I have no way of knowing if that was problem or not! Second one works fine, but I kept the old one....
At least it's not parked in my backyard anymore.

Thanks again.