Pump Vanes/Service Kit: You need the vacuum pump service kit, P/N 3420-10008. The kit includes instructions with diagrams, but do not follow these instructions.
Instead, follow this procedure:

1. Turn off the pump power via the labeled switch on the Service Panel or shut off the H2M using the Key Switch.
2. Remove the pump front cover located at the bottom section of the H2M cabinet. Inspect the cabinet fan filter that covers the air intake slots. If it is dirty, clean and return it. You can blow dust off the filter with compressed air, and the filter can be immersed and cleaned in warm water. If you cannot clean the filter, replace it.
3. Let the pump cool until it is no longer too hot to handle.
4. Disconnect the inlet and outlet sample tubes from the pump, noting the location of each tube so that they are reconnected to the correct fitting.

5. Remove the two bolts on the pump plate (below the pump).
6. Slide out the pump to the front of the cabinet. Then, lift it and rotate it so that the pump head is facing you, with the motor to the rear.
7. Remove the two end caps and their O-Rings.
8. Remove the 5 bolts on the Muffler Box and tap it lightly with a small hammer to break it loose.
9. Scrape off the gasket between the muffler box and the end plate.
10. Remove the 6 bolts that hold the end plate to the body.
11. Remove the end plate and the 4 Vanes.
12. Use steel wool to clean dirt and dust caused by the old vanes. You can blow dust off with compressed air if system isn't located in a clean room
13. Install the 4 new vanes from the kit so that the beveled end slides into the slots in the same orientation as the old vanes.
14. Hold the end plate to the body and install the 6 bolts using a torque sequence.
15. Install a new gasket from the kit between the end plate and muffler box.
16. Get 5 new bolt gaskets from the kit and replace the old ones before bolting the muffler box to the end plate. Screw in the bolts but leave them loose.
17. Using the 2 new O-Rings from the kit, screw in and tighten both end caps. Throw away the felt filters in the kit. No filters are used in the H2M pump.
18. Tighten the bolts, attaching the muffler box to the end plate.
19. Restart the pump while it is still pulled out. Make sure that you have a strong suction and that there are no irregular noises or other problems.
20. Slide the pump back in place and reconnect the tubes and pump plate bolts