So I started the cleaning process with my T800, T1000 and Medicom Boba Fett. I figured the plastic clamshell packaging would have protected them from the damp and it’d be better to start with the easier problems first.
I was pleased to find out they fared quite well in their boxes. Boba Fett has some staining where the chest plates meet his tunic, I think that’s likely to be the adhesive breaking down with age and lack of air. The T800 will need a new pair of trousers and bet to go with it. Upon handing, the belt literally crumbled in my hands!
With that out of the way, I set up a plastic bowl filled with a 1:4 mix of distilled white vinegar and water. The bodies and all other plastic parts were soaked for about an hour and a half, then placed under a running tap. The clothes were also soaked (separated into lights and darks) then hand washed with detergent. Pleather items have been set aside for another time.
the original medicom Boba Fett only had pleather for his holster, but it felt more like suede, doing any treatment on it will result in a darker tone. Just be careful with Medicom body as they are fragile.
Usually i do not recommend touching the pleather if they are old, but since you have removed the clothings i guess you would have to flake them off but be careful not to lose all those buttons etc.
And since you soaked them in water (i would have recommended just wiping) make sure they are totally dried including inside the bodies.