I would consider 12,000km on rings quite a bit and personaly would be replacing them (though it does seem to have good compression).

Andy's bike had almost identical problems untill we got inside it and found dead seals etc.

However Andys bike has never really been a good kick starter but bumps with ease. Mine on the other hand pretty much always goes second kick unless I dont turn the fuel on
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If I have to take the carbs off once more...