Nia

Photograph front, side and back with your arms down, and mark the drag lines directly on the calico in pencil. Drag lines point at the place that needs more room - follow the line and it takes you to the problem.

Write on it, slash it open, safety pin a wedge in. It is a $3 piece of cloth that exists to be abused.

Soap the bead line too, just to confirm it is only burping under load and not weeping constantly.

Generic walking feet fit most low shank machines and work fine for twill. You do not need the branded one.

Push a fingertip up on it gently. If the plaster gives at all, stop testing and start opening.

Slow down. Not a joke - on old mechanicals the loop forms late, and at full pedal the hook arrives before the loop does. Half speed fixed mine permanently.

Middle path: an overcast foot plus your machine's overcast stitch. Not as fast, looks 80 percent as tidy, costs almost nothing and needs no extra desk.

The top edge is definitely bare. Nobody ever paints the bit you cannot see.

Do I replace all three screws in the leaf or just one per leaf?

If you hate the result after the first coat you can still decide to skim. That door does not close.