1982 Johnson 50 hp Outboard revving very high when engine in neutral

[cizara]

Hi, I was running my 1982 Johnson 50hp outboard at 4000 rpm and coming into the launching ramp and when I pulled back on the shift/throttle lever the engine raced at very high revs and I had to stop the engine immediately with the ignition key. The engine is a J50BELCNR. I later found that the throttle shift lockout lever was out of place and a piece had broken off, but that might have been because I pulled back hard on the lever to get the engine to throttle down. I have opened the control box and jury rigged the plastic part so it slides in the proper place again, but the engine when I try and start it, races uncontrollably and I have to switch off immediately. I now think that the original problem may be in the carbs or perhaps an air leak and that I fixed the secondary thing in the control box. Any ideas where I might look? I have checked the throttle and gear shift cables and they are fine. The carb linkages are fine and both internal plates open at the same time and are closed when the engine's in neutral. I "think" that the compression when I turn the flywheel (plugs installed) is lower than normal as I can turn it with one hand on the flywheel and I think it used to be harder than that. I am stumped and don't know where to look first. I would appreciate any advice.