Hello all,
I have experience removing and working the area of the compression posts on Commanders, don't know if there are any outstanding questions that I can help shed some light on. Here's a couple of points though:

1) The compression post is schedule 80 anodized aluminum.
2) The sole was installed first, then the post lowered down through the forward hatch and inserted into the cabin sole hole at a slight angle.
3) The lower end of the post sits on a built up fiberglass base in the bildge. Most likely with wood somewhere inside. The post itself is not glassed in.
4) The wooden wedge between the top of the post and the underside of the cabin is made of teak. The wedge is necessary for the same reasons the mast base has a slope to it.
5) Pearson cored the entire cabin roof, to include (unfortunately) the area immediatedly under the mast step.
6) The core is 3/8 inch end grain balsa.
7) Any detected movement is a sure sign that the balsa's integrity has been compromised. ie, water intrusion followed by rot / decay.
8) No work should be attempted with the spar (mast) up.
9) To remove the compression post strip away the very light tabbing around top of the post and with a block of wood drive the top of the post directly forward. Remember, the post was installed through the cabin sole hole at an angle and will come out at an angle. The biggest challenge will of course be in overcoming any downward movement the cabin roof made due the core failure.

I'll leave it at that for now, unless there are more questions of repair, etc..

Thanks,
Chance.