Robert McKevitt, 27, was working at a warehouse in the city of Milford when the incident occurred last autumn.
Mr McKevitt said he deposited a dollar in the machine, but his Twix bar snagged on a spiral hook.
He then used an 8,000lb (3,628kg) forklift to shake the machine, according to his employer.
“That machine was trouble,” Mr McKevitt told the Des Moines Register, saying he banged on it with his hands but to no avail.
“They fired me, and now I hear they have all new vending machines there.”
The former Polaris Industries employee allegedly used the forklift to pick up the vending machine six times and drop it nearly 2ft (61cm) on to a concrete floor.
Three confectionary bars are said to have fallen out.