The little riveted points you mention are pivots, there are a bunch of them. What you can do is spray a little lubricant in each pivoting part of the derailleur, then physically move it side to side by hand a number of times and it should loosen up. Pull it towards you and then push it back, 10, 20, 30 times.
It might take a bit of force to start with and ...
It can be dirty, but it can be inside the cable and not on the derailleur itself.
See solution here:
Shimano Deore front derailleur occasionally sticking
It can also be the L-screw, or the derailleur position, or even both. Check the L-SCREW ADJUSTMENT section of the ParkTool webpage.