1998 Blazer ZR2, Stuck in 4wd HI; goes 4HI/4LO ok, won't go to 2wd HI. I can switch from 4HI to 4LO to 4HI all day, but it won't go into 2HI.

I pulled the battery and tray out and found the diaphragm sucked in, pulling the cable. But the cable was rusted through the outer jacket and totally frozen. So I managed to remove the cable from the diaphragm and transfer case, put in a new cable, verified it was pulling/pushing the actuator in the transfer case. Then I hooked it back up to the diaphragm, put the vacuum line back on the diaphragm, but it still stuck in 4wd. The diaphragm was sucked in (collapsed) when I checked again, so I removed the vacuum line, allowing the diaphragm to expand and release the cable, thinking that's what was holding it in 4wd. NOPE.

Check the 4wd fuse - that was ok.

When I try and put it into 2HI, there are 3 clunking noises coming from the transfer case, like it tries 3x to go into 2HI but never does.

Can someone help!