Mich. Comp. Laws § 168.587: Primary elections; voting machines, straight ticket and excess voting prevented.

Sec. 587.

Whenever a voting machine is used in a primary election, the party levers or bars, if any, shall be locked against voting so as to prevent straight ticket voting, and the machine shall be properly arranged so that the elector may vote for as many candidates for each office as there are candidates to be nominated to that office and no more.