Entrance will become active once ALL group members have released their Pocketed Boom Burble; then is a group-wide zone-in.
Find a way to destroy the Ulterior Mechanica
Follow ramps up, slaying clockworks as you find them, to reach the Clockwork Gate Lever ( -33, 14, 113 ) /waypoint -33, 14, 113. Activating the lever opens a gate at ( -2, 14, 118 ) /waypoint -2, 14, 118.
Note: The fire grate does % based damage, avoid it.
Next, head downhill and continue clearing clockworks.
Note: pick up Boom Burbles while clearing, 5 are needed at the end. Get more if you use them against mobs. They DO respawn, so backtrack if you run out.
Return to the gate and head uphill, once again clearing clockworks until "You hear the grinding of gears as massive doors are lifted!", indicating that the giant doors are open. All clockworks must be killed for this to happen. Check behind machinery.
Click through three sets of gates to get to the Central Contrapticus ( 330, 0, 0 ) /waypoint 330, 0, 0. Here you will face an encouner of heroic (3 v) clockworks announced by the message "A threat is detected!".
Note: Destroy them, if needed using Pocketed Boom Burbles. There are three sparkling piles scattered around the room (possibly even behind the Central Contrapticus) that can be clicked to obtain more Boom Burbles
Approach the charged field and send Boom Burbles to destroy all of the 5 components. Each time you destroy a component it spawns more clockworks for you to defeat.