Rolling nothing. While DRIVING. Tap the gas and let off to facilitate the gear change.

I changed the ATM fluid in the transfer case last night using the synthetic Mobil 1 recommended on the sight. For some reason now I cannot shift from 2wd to 4H and from 4L to 4H on the fly without the gears grinding. I tried to adjust the linkage but am not clear why the trunion bar needs to slide. It is locked in place by the bolt and doesn't move. I feel stupid but don't get it. The old fluid looked like new. Nice and red and didn't smell funny. HOpefully I didn't do it for no reason. Any thoughts? Thank for all your input.

Charlie, the trunnion is supposed to stay stationary on the shaft.

Re-read this:

Here's how the factory suggests you shift the transfer case and I've been doing this since these things were new and I worked at the dealership. Quoted from the owner's manual.

"To engage, shift the transfer case lever from 2H to 4H while the vehicle is moving at any legal speed". I let off the gas, throw the lever, and then tap the gas and let off.

4L position: " To engage, slow the vehicle to 2-3 MPH , shift the transmission to Neutral, then shift the transfer lever to the right and pull firmly rearward to 4L".

When I tried to move the lever from 2H to 4H at any speed other than not moving I could feel and hear the gears grinding and it not letting me shift. Since this is normally done while moving I figured there is a problem. Though maybe the fluid since it didnt do that before.

Keep moving at speed and throw the lever quickly. Let off gas, throw lever, tap gas, let off gas.