it might be getting oil in through the center case gasket,and the right side oil seal -is not a (supposed thing it is a fact) so is the center cases gasket!!, some models dont have a center gasket, they use the yamalube or liquid sealer ****, i make one from a roll of gasket material and seal it with shellac-never had a prob
check the reeds
the silencer ? just get new packing material wrap it tightyou can use a rubber band to hold it and slide it in-try klotz oil 40:1
good luck