I could swear it's the big cover on the TOP (not the side) with FOUR (not three) screws hodling it in place.
when you remove it, there's a FOOT long spring. Take it out.
Stick your finger into the hole, there's an INCH wide grey slide (plunger) with 2 inches (not little) long needle attached to it. Slide the plunger out somehow.
Now, look into the plunger, where the spring was. There's a weird shaped metal piece (with slits) held down by two screws. It has a hole in the middle with needle end sticking out. Unscrew screws. They are easy to strip, be careful. Push hard, turn lightly. Under it is the white washer.