You should find the needles are different in each carb, not that I suspect it has anything to do with your problem, just letting you know as you are rummaging around in the carbs checking settings.

As previously mentioned, do some compression checks - one hot, one cold. It sounds very much like a possible case of "fair wear and tear", and due a top-end rebuild.

Poorer performance in the wet would certainly suggest corroded terminals somewhere however, so a good clean and check of everything you can lay your hands on (don't forget the earth [ground] points too). Corrosion and/or damp can indeed cause more resistance in different circumstances, and then possibly failure, and lead your fault finding astray!

Andy.
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