putting any lube or cleaner on that part will do nothing since it sounds more like the signal arm is the problem. That little flap is connected to an arm that reaches all the way to the counter side. That aclick you hear when you cock is the mechanism involved.

Open the top?

2 screws.. one in each corner. Then inside.. 2 more screws. Peel the leatherete off the center of the lever.. unscrew the large brass screw.. carefully lift the lever without dislodgeing the spring below it. Put the screw back on.. now lift the top n jsut be mindfull of the flap by the hole in front of the lever. Put back the lever n cock away to find your porblem.

Check all the screws to see they are snug.. common for some to work lose. When cocking see if the casting at the stop of the lever is cracked? Snapping your lever back tends to beak this casting n causes problems such as yours.. early sign.

AS you cock you will see how the mechanisms work so jsut followo the levers around. OH load some backing paper in the back to simulate film runiong through.

Yes maybe a tiny drop of WD will help in a few places... but it is a very tiny pin head of a drop. almsot molecular. no need to juice her up.