After you get Duncan out of the shack you need to clear his mind.
His mind is numb from all the fluff use.
If you would give him some more fluff?
Check out the pipe at the lower area. ?
Use the sludge to get a worm.
You have the worm from the sludge? Would Duncan like that?
I think you should make a call... ?
Use the phone and talk about the worm.
Go talk to Duncan. ?
You can now push him off.