DETROIT — More than 3,000 Detroit election day poll workers will undergo mandatory testing and re-evaluations ahead of their 2018 gubernatorial election cycle training.

The city’s Elections office says the testing and evaluations are to improve operations at polling locations and will be held through early April.

Clerk Janice Winfrey says that by “re-evaluating each poll worker, the department can identify the issues and customize training.”

Michigan’s elections bureau ordered an investigation in December 2016 into ballot discrepancies in a small portion of Detroit’s voting precincts, after the discovery of a polling place where 300 people voted but only 50 ballots were properly sealed in a container.

Detroit elections officials told the state that in the one precinct, the 250 missing ballots were left in the tabulator bin.