Yep, I agree. From all I have read, it sounds like it is the lock nut. The dealers say the part is special order from Germany. Kent at M$$ource has it and I can buy with 2-day shipping. I have no idea where I would get the cap nut. Any ideas? I suppose I could look through a junkyard if I absolutely had to. I was able to adjust all of the other valves.

The strange thing is after playing with all of the valves, I don't believe the bottom lock nut is the same as the others. It seems just a tad bit larger and my 14mm wrenches do not fully grab onto it.

Dkr.