Just got a 1970's 850 Mercury 2 stroke outboard running after years of sitting, the only thing I did to it was clean out the mouse nests, added fresh gas, squeezed the bulb and she fired right up. Problem is, she wont hit full throttle. The top carb butterflies seem to be extremely hard to open and close, they don't follow the cams like they should and I can't even move them easily with a screwdriver by pushing on the top arm, these should open and close freely, is there an internal linkage that may be binding up or something. I'm not a 2 stroke guy or an outboard guy, diesels are my fortay. Previous owner said ran fine, just fell flat when you hit the throttle, go figure! Any ideas?