[Tom Wesenberg]

I adjusted a guy's horn at French Lick and also couldn't feel the clicks, so I suspect he was missing a part. The screw head and the bracket it pushes against should both hve radial serations to hold the screw from turning on it's own.

It's important for the diaphram to be correctly positioned so the wavey washer strikes the wedge correctly.

When you screwed the cover onto the horn, it pulls back on the motor frame, which may have been enough to make the wavey washer clear the diaphram wedge. Try turning the adjustment screw clockwise as mentioned to make a slight contact.