If your dock is normal strength ? You can do all the idle in forward gear while tied to the dock. Up to a very fast idle should be no problem for the dock. After reliable dock loading tests. I take a boat out on the water for higher power testing.
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.