I was recently at a company with many older (30+ years) home-made molding machines. Although the machines have a large number of moving components and cams, the molder did a great job of adding full guarding around the entire machine. This guarding was not particularly complex, or expensive, but it is a great way to ensure your employees stay safe.
Make sure all your older machines are well guarded to protect your employees and your company from liability. Even though your machine was legal the day it was purchased does not mean it is not a liability today.