Find the weed wacker and attach it to the robot body, which you also have to find and activate.
you cant
You go to the bottom of the vines and click on the windows and they will kill the vines.
You just click the windows where the vines are coming out of. You click all three and the windows will close snapping the vines.
If you look down, you'll see three windows where the vines sprouted from. Go down and click on them to snap the vines and free him.
use the weed wacker. and press spacebar
When Sprocket is grabbed by the vines at the Captain's Quarters, slam the metal windows shut to cut the vines.
It is at the far left past the living quarters. It is covered by vines that have to be removed.
click on all three of the window to free the robot
Take it to the vine spot and click space bar to cut the vines. (it is to the left)
There are no windows that open inward on Steamworks Island. There is a skylight in the City Hall that can be opened with the Multi-Tool. You go out the hatch above Zack's room in the living quarters, to reach the Mech Crank on the vines.
There is a very old Dirty Beaker in the Steamworks Museum (far upper right). Use the machines and climb the vines to reach the beaker. You need this at the Greenhouse in the Laboratory (Production zone, right side of the island).
It is by the "tightrope" vines at upper left past the Living Quarters. The only way to get there is through the quarters using the key, which is in a closet all the way across the island in the Research labs. (see related question)