Guide is based on info I found here: https://wasteland.fandom.com/wiki/Working_Stiff
When you get inside Steeltown's Admin Level for the first time, after a small dialogue with spokeperson Bennie Bianchi, enter the room to the right and talk to the NPC Oluwademilade. You'll have to take a series of three tests, and complete a task after each of them. The first two are fitness and cognitive capabilities, which will give you the nut tightener and nut loosener jobs. To complete the job find the item "MACHINERY" near the elevator, facing the weapons vendor in the west side of the Admin level.
After completing them, you'll take the target practice test, which will place you as a fire suppression expert.
This last part grants you a full set of pyro gear and your job is to relieve Keith down on the factory level. Refer also to this:
Once you relieve him, return to Oluwademilade to collect your reward.
Then talk to Oluwademilade again and after taking one of the same tests again you will be recieving the only two jobs of nut tightener and nut loosener, one at a time. Simply complete these two jobs until achievement unlocks.