Stuck with The Hero of Gavel Quest

I was doing this quest, and forgot to get Soft Slime.
Now I'm at the final stage within the cave, where you need to get the parachute and soft boots using the sewing machine.
I tried going back, but the path is blocked by invisible blocks near the big spider web.
I also tried to make hard boots(saw a forum post), but the machine just won't work with only hard leather.
Finally I tried using /fixquests, and the game decided to throw useless items in my inventory that I can't get rid of. While doing that, a lava bucket was given to me and I thought it was related to this quest so I threw out the actual lava bucket I need and kept the useless one instead.
So basically I'm stuck with no other option to do, it seems. Is there any way to fix the quest other than getting that slime with another character?

i had to waste 3le out of my poor bank and now i can't do shit
i hate this quest >:{

 

luckily, you only need to get one of them to save siegfried, otherwise you could just let him die with the hard boots (which the last part should have the stuff for)! Fun stuff

And about this, you should be able to get a new bucket in the last cave, as well as putting lava in it again!

I mean who doesnt, saving people is hard :/