Debris from the degraded foam has almost certainly found its way into the shutter.
Any solvent will only spread it out and move it around. Years ago just for curiosity, I removed a similarly-affected shutter and immersed it in solvent - while immersed I cocked & fired the shutter many times, tried (carefully) jetting & brushing solvent into the edge of the housing. In total the shutter was submerged for hours in a very effective solvent, cellulose thinners.
When removed & dried there was a slight improvement but not enough to be of any use whatever - I still had to strip it to clean it properly.
Unless you can do this yourself your camera is definitely well beyond economic repair.