Originally Posted by badmother

Got a stem or two like this somewhere and I think your suggestion is right. This is a normal quill stem with a big plasticwheel instead of the normal top and I think the wedge is stuck inside the steering tube of the bike. I hope it can be without crushing the plastic. Maybe the plastic can be replaced but the owner may want to keep it original.

Could the plastic be remowed so that you can hit the bolt under it? Maybe soaking the whole stem in molasses or amonia like the guys and gals in Classic and Vintage.