The Schaublin 13 lubrication pump deserves a service now that there is no oil in circuit and it is easy to disassemble.
Given its simple design, to service it you should just replace three or-rings. Two of them are the seals of the pumb body, that avoid oil leaking from the tank. The most interesting to replace, however, is the o-ring of the piston. To replace it you should first free the piston by pushing a pin out. This can be done by aligning a specific hole on the piston: this allows to reach the pin with a pin punch drive. The following pictures show this process. The right sizes of the three o-rings are tabulated in the blog entry about o-rings.
The next picture shows the hole used to push the piston retaining pin.
![](pisto1.jpg)
After aligning the piston pass through hole, you can push the retaining pin.
![](pisto2.jpg)
![](pisto3.jpg)
This is an exploded viwe of the pump piston and one of two ball valves inside.
![](exploded.jpg)