I had a chance to talk with a very experienced Winter bike guy...he confirmed it is the shifter and pointed me to the setup local high-end users have...which is a shimano bar-end shifter with an adapter for use on mtn bikes. The grease in the factory direct pugs shifters can cause problems. If my replacement bike (due to frame size) also has issues I'll probably degrease the shifter and see if that takes care of the issue. If I continue to have problems I'll replace the shifters but it's not cheap so we'll try a simple solution first. I've not looked at them closely to see if they can be disassembled and greased with a Winter grade grease. We'll see...