You use a lobster (!) to turn the crank on the lighthouse light, which will scare the seagull from the school's bell tower.
To get the lobster, catch the photo blowing next to the lighthouse, and take it to the photo shop. The owner will swap you some diving gear, which you can use next to the lighthouse. Dive and recover Cap'n Salty's lost lobster trap and he will give you a lobster and his jet ski keys (use them once you look through the artist's telescope).
Turn the light to scare the seagull, and then you can fix the bell.
(see related question)
Use a lobster to grip the crank on the lighthouse light. (see related question)
On Big Nate Island, you use a lobster (no kidding) to turn the lighthouse crank. (see the related question below)
Use the lobster to crank the lighthouse light. Turning it left will scare the seagull from the school's bell tower.
on top of the lighthouse
There is a lighthouse on Big Nate and Vampire Curse Island.
You use the lobster as "pliers" to turn the crank on the lighthouse, so that the light scares away the seagull from the school bell tower.
The lobster can turn the crank on the light at the top of the lighthouse, scaring away the seagull from the school bell tower.
It needs to be dark
Use the pieces of metal jutting out from the lighthouse to jump on and quickly ascend to the top.
The lobster claw grabs the crank to turn the light on the lighthouse. When the light turns left, it scares the seagull away from the school's bell tower. Now you can fix the bell.
you use it to turn the light on the lighthouse
You will have to swim for it : the lighthouse is on Big Nate Island, not Counterfeit Island.