Any 25 cent mech will work. I prefer the metal ones. There are three holes on each side, and usually come with two studs screwed into those holes each side. For the coin door on MMR, with the mech facing you, you don't need any studs on the right side of the mech, and on the left side you need studs in the top and bottom holes only.
All you need is the mech. On the coin door all the mounting stuff is there. Lift the plastic flap up, snap the mech in - flat side to the coin door and stud side to the outside. Lower the plastic flap so it hooks the studs, and you are good to go.
LTG : )