Do you have the owner's manual? It will tell you which coil to purchase. The coil # should also be on the coil on your machine.
Doesn't the "complete" mechanism come with the coil?
Why are you buying the entire mechanism? Are they really corroded or broken? Replacing the coil, coil sleeve and flipper bushing along with a good cleaning should solve the problem. I would check the switches also.
I would listen to Jar. I have never had a weak flipper on my machines. Just an inop coil.