Here's an excerpt from the walkthrough -- see if you can spot what you might have missed doing up to this point. There aren't too many steps, so it's likely something small:
(Main Street)
Talk to Leopold (the robot calling out to you)
Ask what he has for sale
Click on the crowbar
Open your inventory and look at the burnt energy sensor
Trade the crystal for the crowbar
Go to the information kiosk
Type "LAW"
Take the printout
Open your inventory and LOOK at the printout (important)
Walk NORTH
(Tower base)
Look at the door and note that the damage is superficial
Go back to Main Street, and take the LEFT path
(Crash site)
Use Crispin on the cable to move it
Use Crispin on the floater
Continue to the left to go to...
(Courthouse)
Use the lamp on Crispin
Go back to the Crash site
(Crash site)
Use Crispin on the floater (get copper wiring)
If you still have trouble -- let us know.
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"Bleat, Watson -- unmitigated bleat!" ~ Sherlock Holmes