I was having trouble shifting from high to low gearing (the differential lock was working fine). Searching about it, seems like the general consensus was either clean it out or a faulty solenoid - which is an annoying fix.

Definitely explore the idea of cleaning out the linkage. You can see the connection from under the vehicle and are just barely able to get some cleaner sprayed up there. My method of attack was PB Blaster, Parts Cleaner, WD-40.

After about 30 minutes in between each soak, it shifted into neutral and then low gear without problems (while running, in neutral, slowly rolling helped).

I've read that it is recommended to shift into low fairly regularly regardless of need. I hadn't for over six months, but plan to exercise it several times a month moving foward.