[Roadtrip]

The brass plug in the bottom is the well for the hydraulic piston for the cold start system. You'll get some drainage out of it, but due to the internal casting, they'll still be some oil left in the logic section.

I've found the easiest way, if you want to remove as much of the old oil as possible, is to fish a vinyl tube down in the the bottom and suck it out with a big syringe. However, just adding some fresh oil is sufficient to stay in good condition. Excess oil will just drain to the sump.

You shouldn't mess with the solenoids, or you have to retune the pump. The easiest is just to carefully remove the barometric compensator (3 screws). Since there's no pressure in the logic section, you shouldn't have to replace the gasket, at least I've never had to.