All the shafts last time I looked were blocked, many had been sealed by placing a large boulder in at level of solid rock. There have been odd rumours of shafts opening up, but none substantiated that I am aware of.
I think if you want more information most people active in the area will be reluctant to give it in an open access site such as this, for very obvious reasons, but if you contact any of the groups active in the area privately there would be a lot more information on what is accessible than can be given here.