The mechanic at my dealership said it should be set just a couple clicks from the top and if it needs so it will self adjust from there. He did this with my 20 tooth gear and it's been fine since.
The book wants you to set the tensioner at the first notch and leave it. It's an auto adjusting tensioner, and from what I am told, by setting the tensioner "tight" at first, you can actually do some damage to the bearing in the jackshaft...Not that you could really screw anything else up inside of that wonderful design.
With the 19 tooth gear the adjuster will adjust itself to the tightest setting which is still not quite tight enough. I got approx 50 miles in before landing a big jump and the adjuster popping out of place and breaking. Now going to the 20 tooth top gear. Just some info that may help out some people.
I had a 19T and 20T side by side last night when I decided to look at the chain- and like you ^^ found the adjustment to be quite lacking in the 19th-
I stayed with the 20T and after runnig runnin the sled the adjuster is dead nutz in the center of adjustment alowing ample deflection for AIR time