Borderlands 2 Cleaning Up the Berg mission is triggered automatically after we complete the Blindsided mission.
When we acquire Claptrap’s eye we need to find someone who can attach it back. For that we go to Liars Berg, located in the Southern Shelf area, where we will meet Sir Hammerlock.
Borderlands 2 Cleaning Up the Berg is a story mission, and it must be completed in order to advance through the game.
As soon as we complete this specific quest, we can unlock additional side-missions, as well as a new story quest, named Best Minion Ever.
You’ve found Claptrap’s eye, but he still needs someone to plug it into his socket. That someone happens to be one Sir Hammerlock, who currently resides in the town of Liars Berg. Claptrap wants you to head there now.
First thing we need to do int Borderlands 2 Cleaning Up the Berg is to jump down to the towns gate and shoot all the Bullymong enemies.
Then we wait for Claptrap to open the gate, after which we kill the enemies inside the town.
Next, we follow Claptrap in order to meet with Sir Hammerlock. We give Sir Hammerlock the eye to fix Claptrap and we go with him so he can restore the power. Now we can talk to Sir Hammerlock to finish Cleaning Up the Berg mission.
At this point, a series of new side-missions become available.
We can opt to complete them first (recommended), or we can continue to play the story mission we receive from Claptrap. One of the optional missions we activate is This Town Ain’t Big Enough.