Foams inside the F2
There are internal (those you can't see) as well as external (those you can see) foams in the F2. Over time, internal foams degrade as external ones, become sticky and disintegrate.

If the foams fall on the slow sync mechanism, then all the slow shutter speeds would not work.

If the foams fall on the shutter curtains, then they can pull off the rubber coating on the titanium shutter curtains, see Photos below. However, once cleaned off, these spots have no harmful effects on the shutter curtains, nor affect the shutter speeds.
Foam fallen on shutter curtain,
case 1
Foam fallen on shutter curtain,
case 2