I have 5 of the FX lightsabers that were released in the early 2000s when Episodes 2 and 3 came out. I also have about 20 of the various Power of the Force lightsabers that were released between ’97 and ’05. Unfortunately, my basement flooded 6 years ago and the Power of the Force lightsabers were coated in muck as they were stored in the basement. I’ve had to go and clean them up and thankfully, some of them still work.
I damn near cried when I found them after we got the water drained out. I discovered that toothpaste is great for cleaning. It doesn’t damage the plastic on the saber hilts, it’s easy to wipe off and doesn’t leave a residue (plus they smell nice afterwards) and the sabers look almost brand new when finished. My main worry was the electronics inside but since most didn’t have batteries in them and they have all since dried out, many seem to be “ok”.
I’ve been debating on whether or not to do a Youtube video on the cleaning process, at least for my Luke Skywalker (ROTJ) and Vader hilts.