Reached through UPDATES. A valve falls under gravity, can be pushed, and is the one thing that can be picked up and carried (TAKE_OR_LEAVE), and makes a sound pitched by its position each turn it moves. In a chamber whose socket is of its kind (the socket's graphic less 16) it also steers itself, a unit a turn in U and V, towards the socket; when it sits exactly on it -- the same U and V, and 12 above the socket's base -- it activates the chamber.

Activating: the valve becomes a seated one (graphic 4 more, SEATED_VALVE); the screen's inks run through all eight colours twice, with a sparkle's sound; the room's ink becomes white for the rest of the game (through ROOM_COLOUR_AT) and the screen and panel are recoloured (COLOUR_PANEL); CHAMBERS goes up by one, and the twenty-fourth sets WON and ends the game (GAME_ENDED). Otherwise the new count is printed and copied to the screen.

The second test of the kinds, after the valve is found sitting on the socket, can never fail: the valve would have steered only to a socket of its kind. Had it failed, the valve would have become graphic 64, the dying sparkle, and been lost (SPARKLE_STEP). Nothing reaches it (read; never run).