1994 minicab 4x4 4 speed hi/lo Ok here is the deal I have no 4x4 dash light and the 4x4 won't engage. With the key on I can hear the front diaphragm click and puff a little air but no lock into 4x4 when I push button. If I put the truck up on jack stands with it running in gear I can use a pry bar to manually engage 4wd. If I turn the truck off then it automatically goes back into 2wd. Also with the engine off I cannot pry it into 4wd. There is vacuum going into the diaphragm & it does click when I push 4x4 button. I assume that the diaphragm is leaking and the 4x4 dash light must just be shot. Anybody have any ideas?