A small claim shall be tried by the court unless a jury demand is filed by the plaintiff at the time the action is commenced or by the defendant not later than the date he is required to appear. There shall be 6 jurors unless either party demands 12. A party demanding a jury shall pay a fee of $12.50 unless he demands a jury of 12, in which case he shall pay a fee of $25, or, if another party has previously paid a fee for a jury of 6, $12.50.