4x4 frustration

First post from me, I've enjoyed & benefitted from all (well, most) who respond with your knowledge and insights on various threads. Thanks. My problem is on my 242k 2007 4.7 crew cab 4x4. I just had the A/C rebuilt after a blown compressor, installed the air bypass from Hewitt on my own, and now can't figure out why the 4x4 won't engage. Worked when I bought it and for sometime afterward, then left me stuck in the mud one night. I get the flashing "4x4hi" dash light. My son-in-law & I have opened the high drive side (side with vent line) of the actuator on the transfer case - clean as a whistle. He can hear it engage, so presumably that functions. Afterwards, with wheels off ground, most of the time the front wheels would not engage. Maybe 1 in 10 times, the 4x4 engaged completely and drove the front wheels. Next, we replaced the front differential actuator, since the cost was relatively low and I had ordered one off Amazon to have on hand, thinking it was the rear actuator. No difference. I'm not very mechanically inclined and I just came to this conclusion: must be in rear actuator or transfer case, because with wheels off the ground, the rear driveshaft always spins but the front driveshaft just turns maybe 1/2 rotation when I turn the 4x4 switch in the cab. Front or reverse, same thing: turn switch, light flashes continually & front driveshaft moves slightly and stops. I have cleared all but the TPMS lights off the dash, no codes show on my reader.
Our ideas: Although we were careful to keep the gear in the transfer case actuator in the same position, could the actuator guts be aligned and cause this? Could the TPMS, or somehow the VSC system keep the front driveshaft from engaging in the transfer case? Is my transfer case broken inside somehow? It has gone beyond what we want to try without some insight. You guys are the experts - what do I do next to fix this critter? Thanks!

 

Welcome from Ontario Canada , someone will chime in with some idea .