You do know, KEH will pay for the return shipping if you call them and tell them of your problem, right?
Any competent repair person will charge you, on average, 75 dollars or so an hour labor to fix your camera.
I just looked at mine. You can screw off the view finder glass by rotating it counter clock wise. Once you do that, you see there is a glass assembly that (is supposed to) move in and out as you rotate the diopter adjustment. When you pull out the dipoter adjustment knob, it engages and as you rotate, the lens assembly inside moves.
Strictly by feel, the parts feels plastic. If they are busted, you'll need to get replacement parts - which may be next to impossible for individuals.