You have to get the mech crank and the motor.
The unfinished Mech that Zack was working on is in the garage next to Sully's. You need the Mech Motor and Mech Crank to finish it.In the garage next to sully's shop on the left side of the island.
you go in it
The Mech Walker is the key to entering the storeroom and defeating the monster plants that are active there. Once you finish the Mech with the Motor and Crank, you can attach the Weed Whacker attachment and enter the door at the far left of the island.
Go left along the vine and pick up the Mech Crank. Along with the Mech Motor you recovered from the Production Zone, use it to finish building the Mech walker.
Locate the items that can access the information sources on the island, including the helpful robot named Sprocket. Finish building the Mech Walker so that you can battle the plants that have taken over the island, and find the missing inhabitants of Steamworks Island. (for solutions, see the related questions below)
find the mech crank and mech battery
Clearing the weeds from the entrance at far left (the Storeroom) will have to wait until you finish building the Mech walker, which is in the garage next to Sully's. The weed whacker attachment for the Mech is in Captain Zigg's quarters on top of the Hub.
pound it with the mech's weed whacker
You can get the mech crank at living quarters in Zack's room ( go up the ladder and exit the room and walk across the vine and pick up the mech crank)
Easy! Duck like you normally would! Point your arrow down.
You cannot, as it will not jump high enough to get to Main Street again. Thus, you cannot get to the blimp.
Take it to the vine spot and click space bar to cut the vines. (it is to the left)