[david85]

Looking at the photos, that seems to be a licensed japanese clone of the bosch VE rotary injection pump (likely very similar to VW diesels of the era). The Japanes didn't bother to put an actual brass bushing for the shaft to ride on back then, so the case itself is the bushing. In the case of our ranger, they had to machine the top cover and press in a repair bushing.

If it were me, I would remove the pump, if for no other reason than to be able to clean it and keep gunk out when you pull it apart. Its generally easier to do that on a clean bench. Although its front and center on your car so it might not be so hard to do. Just don't wash the pump when its not or running (EVER!). Use some penetrating oil on the pump shaft nut for a few days before attempting to take it off. Sometimes they corrode enough that it snaps when trying to remove it. Also scripe the alignent of the throttle lever to the shaft before taking it off.

Any diesel injection shop should have a few zillion of those throttle shaft seals in stock. Be sure to ask for a Viton seal. They should all be anyway these days but you never know.