What must the workers do to get the NLRB to hold a de-certification election? (2 Readable Detailed Paragraphs Minimum)

The maintenance and food service workers at Prestigious University are represented by the International Brotherhood of Teamsters Union.

The union and the university administration have just agreed on a new collective bargaining agreement covering the next four years.

A number of workers in the skilled maintenance department are dissatisfied with their union because they feel that the union accepted lower wage raises in return for getting a long term contract.

They contact a representative of the Service Employees International Union to discuss ousting the Teamsters as their bargaining representative.

What must the workers do to get the NLRB to hold a de-certification election?

(2 Paragraph minimum)