What should I do with the stone shaft?

Hint 1 of 8:

The chock is holding a counterweight for an elevator in place.

Hint 2 of 8:

If you could lower the elevator, you can probably get across.

Hint 3 of 8:

You might want to knock the chock to get the elevator down.

Hint 4 of 8:

Wait until you find Sternhart if you haven't already.

Hint 5 of 8:

Use the staff on the chock to help you here.

Hint 6 of 8:

It looks like you also need to call the elevator to bring it down.

Hint 7 of 8:

Go down to the room below this to find the controls.

Hint 8 of 8:

The statue mouth will help you here.  See if you can find something to
reach inside for the controls.