So the last post was almost prophetic in its tone. More haste less speed. I finally had to drop into the granny ring (smallest front chainring) on the Adventure the other day. The result on a steep incline was to suddenly stop as the chain stuck and held fast on a cog. Ouch. It is funny but running the bike off the floor on a workstand there was a little stickiness which I took to just be stiff linkers that would work out overtime. Under real pedal tension it appears that this is more serious. Four cogs grip the chain by being too wide for the 9-speed chain. Perhaps a little more careful investigation at the start would have presented the embarrassment of falling off on the hill.
The question now becomes how to fix the problem.