I thought I’d chime in to share my success (thankfully) story. I could shift between 1st and Reverse, to 2nd if I was lucky, and to 3rd was ok. Going back to 2nd from 3rd was hit or miss.
After reading the posts in this thread, I took the cable off. It was stuck and required a lot of pressure on either end to make it move. I hung it up vertically in my garage and sprayed penetrating oil and brake cleaner on each button and the 'collar' that houses each button. I let that soak a bit - then would press each side back and forth a few times.
I'd then flip the cable around and spray the other button/collar to let liquid seep into the opposite end.
After about 2 days of doing this on and off a handful of times per day, everything loosed up nicely. I can now make the cable move with very little pressure and it springs back into place without issue.
I reinstalled the cable and we're back to normal.
Thanks to everyone who posted!