Dozens of former temporary workers at Navistar in Chatham have filed a grievance over their pay after the company denied them severance.
Unifor 127 hopes the issue gets resolved in a week or two before it goes to arbitration.
Seventy-six former temporary part time Navistar workers are affected.
The union grievance says the company wrongly calculated their seniority and time of employment and the employees are entitled to their severance pay.
The company says the closure agreement has been settled.
Unifor 127 says all other issues regarding the Navistar plant have been resolved.