The compression reducer is normally only functioning during very low engine speeds. Such as rope hand starts.
I went to JLM site and read a detailed parts list. Could not find any words like compression release. About any parts.
So we really do not know if it is really the original carburetor for that year ? How do we determine what model that carburetor is with out some identification numbers ?
Seafoam is a SLOW acting solvent. It does not suddenly dissolve all the crud at once and block tiny fuel passages.
I use it 1 time about each year to regain the lost mileage do to crummier modern gasoline.
Just fully tilt it up and lock it there. Transom straps to trailer.
Bow winched tight and safety chain snug.
I know. I have the only good boat that Lowe ever built.