Denzil's straw
In this chapter
The dry straw goes by Denzil's ice; the match he needs is on the grasslands, behind the leprechaun.
Ice melts in a fire, and a fire needs fuel and a flame. The fuel is close: a pile of dry straw lies low on the third floor. Carry it into Denzil's pad and drop it by the block of ice, standing to the left of Denzil (B right next to him only talks) (Denzil frozen in ice).
The flame is a dry match, lying on the grasslands' high path, behind Shamus the leprechaun. The long way there, through Crystal Falls and Keldor's tunnels to the graveyard, shows the snag: Shamus knocks Dizzy back, and he'd only move for a lucky treasure (The little fellow on the high path). That treasure is in the diamond mines.
Back home, then, for the wrench and the dynamite.