Stone cold this morning , with the engine off, I took the hose off the AAR and looked in there with a mirror and a flashlight. It was happily open as it should be.

I started it up, and at cold idle, 1300 rpm, I dis-connected the hose to the AAR and it almost died. So then I tried holding my finger over the opening to the AAR and it idled at a lower RPM, but not smoothly.

After letting it run for a few minutes, I turned it off and looked in there again, and the AAR was completely closed, so it is working properly.

Then at warm idle, removing the hose to the AAR causes the idle to almost completly die again, but if I hold my finger over the opening to the AAR it idles better.

Oops, I didn't try holding my finger over the open end of the tube.

I might just wait until later this summer when I have planned to take the engine out, and then I'm sure it will be easy to see what's going on back there.