Going by the manual, looks like the top screw just under the anti cavitation plate, it looks like someone has been there before.
I assume it vents here. Manual says the oil will flow out the oil level hole under it.
https://www.manualslib.com/manual/87...0.html?page=38
Get yourself a pump dispenser. Quicksilver do one. Honestly you’ll never go back to squeezing 237ml tubes again. Turns a messy job into a relatively easy one. Swap out the washers as a matter of course.