Hey Boraxman, I know why mine is adjusted all the way out. I forgot to take the old belt with me for a good measurement, so after 1 or 2 belts and a couple of guesses, it's always longer.
As for price, It's worth it. Last year I went to the big Pomona swap meet and most people wouldn't even have the upper arm. I found tons of lower brackets. Most guys that had the complete set would sell them for 25 bucks and if you tried talking them into selling the upper bracket, they would ask 20 bucks.