Yup - I went through to sump 4 when I was younger - cant remember which year it was. must have been late 80's early ninetys.
Spoke to kieth in HnH the other day who reckoned it was still up. though I dont know how recently he'd been down. Its worth a look if it is. wierd following the dive lines though bone dry passage.
Apparently you can go upstream a fair way too.