What can you do if you own one of these "strange" twin chamber pumps and find that it will not produce vacuum? Usually one or both of the rubber diaphragms are cracked or torn. Since these are not available, if you want your pump to work again you have to get creative.
Problem & Solution
Common among these chassis:
Kent has come up with an instructional video on how to take new parts from another pump and modify them to work in an early 300SD's pump. Watch the video and he will explain what parts you need and how to modify them.