I could try, but can't even see the plug!
When the coil pack is removed, there is a metal spring in the centre of the rubber seal, about 3" long. This seems to form the connection between the coil pack output and the top of the plug. The spring just pulls out of the rubber, leaving a hole in the center of the rubber that goes down to the top of the plug I suspect.
I've no idea if there is a metal cap on the end of the plug (i.e. attached to the rubber seal), or whether the spring just presses directly against the top of the plug. There is scope for poking something thin down this hole when the spring is removed, and I've already squirted some WD40 down there.
I've even considered blowing compressed air down this hole in an attempt to free it up, but not actually tried this yet!