4wd actuator issue

Hello Tundra people.

I was having problems with my 4wd not engaging last winter on my 2007 5.7. Over the summer it would engage no problem. Once it cooled down in November it would not engage again. I read about the corrosion on the motors and i was going to take it apart but lo and behold the screws were not going to come out with out complete destruction. So I went ahead and ordered a new actuator. When I took apart the old one it looked just fine no corrosion. I Installed the new one timed it several times double checking.4wd would still not engage. So I took apart the front ADD actuator it didn't come apart nicely so I ordered a new one and installed. That still didn't fix my problem. What I have discovered is that if I take apart the 4high and 4low actuators and enage 4wd it will work perfectly. The ADD Locks up the dash light works and so does 4low. If I put the actuator together the 4high pulls out then a few seconds later you can here it pull back in and 4high flashes quickly on the dash. I thought the problem might be in the tranfer case so I got a used one. Before I installed the used transfer case I plugged in the harness and it is doing the exact same thing the old is. I even put the new actuator parts in and I am getting the same thing. 4wd high engages dash flashes slow then you can the 4wd disengage and 4high flashes quickly. Again if I take it apart in my hands it works perfectly ADD locks and 4high will stay lit up on dash. If anyone has any pointers or suggestions I would appreciate it very much thank you for your time.