I've heard the adit was open as well. Jope's shaft is very close to a major fluccan, so, it's quite possible it was all run in and unimpressive. As you walk up the track, there is a crack/hole in the high side of the track, about 4ft above the level of the track which has water coming out of it. In my estimation, this would perhaps indicate something to do with a blockage in the adit.
Jopes was deep and if I remember rightly, was also a fair sized shaft, since the wall is intact, it's unlikely there was anything big bulldozed into it. Probably concrete sollars or similar.....why they would have capped it when there was a perfectly good wall around it, I have no idea. If I also remember rightly, it's in the wrong place for a farmers bin.