So all these methods are "shotgun" approaches to hopefully find the thing that will "fix" the problem and not start new ones... (Like fuming poison in your home to kill one bug...)

There are several reasons a shutter can start running slow, then stopping, and where even normal operation can damage it due to undue forces applied to it...

If you haven't had a CLA applied to it recently, it's like starting a 50, 60, 70 etc year old car without service... Bad idea... A series of mechanical linkages have to move free, and not just move but has to hold time tolerances for proper exposure...

I'm a tech (but only for private projects), and I know there are others have figured it out, but most will probably damage a unit if attempted... For instance, how would you know if iris blades are not metal, but paper or other materials that would be damaged by a solvent flush or soak??? And there are other devils in the details too...

$100 for a proper CLA is not much compared to a cheap car repair or dentists bill, and will give long life and use from the shutter...

Why chance it if you have no idea what you are doing???

Steve K