Another turd gen can't engage 4WD

I have a brand new, shiny, no-prize for anyone who can help with this:

When i try to engage 4WD I can get into 4 HI just fine, but 4 LO will not engage. I recently swapped my front actuator tube for an FJ non-actuator tube and left a functioning front actuator plugged in. These 2 facts make me assume the problem is with the T-case actuator. The weird thing is, if I turn the dial to 4 LO it just flashes whether I try to move forward or reverse. But, if I turn off the engine, 4 LO is engaged when I restart. Also, I can't disengage 4 LO unless I turn off the engine again.

My last offroad trip was about 4 months ago and, of course, everything worked fine then.

Has anyone experienced this particular phenomenon?

 

Have you had this truck a while? 4 lo doesn’t shift unless clutch is held all the way to the floor. I know the manual says to be moving a few mph, but I have much better experience sitting still with clutch down. In fact, mine has never NOT shifted into LO when I was sitting still with the clutch down.

 

I've owned the truck since new. I can't say that I had the clutch to the floor. I just tried to engage as I always have. But I'll give that a try an see what happens.


Edit: I tried the clutch to the floor, not moving at all, and it engaged and disengaged like butter. I'll keep testing this as I have a trip in 4 weeks and I don't want to drive all the way to Colorado just to find out my 4WD doesn't work, again.
Thanks for the tip.