Kubota injection pump

We have a Steiner with a D600 engine. We took apart the injection pump (because we're hard headed and didn't want to send it off) the other day because the middle cylinder wasn't getting fuel. It turned out to be a broken compression spring, which we ordered. However, we noticed that the buttons(?) inside the assemblies are marked 00, 12, and 17. We figured out why-different thicknesses, but we don't know which cylinder assemblies to put them back into. Ah'm not a smart man. Any suggestions?