I am cleaning my 60mm armies. The newest ones are recasts, but the vast majority of them are 40 to 60 years old. I have had some of them since 1958 and got many off eBay. Many are very dirty. I am using these clear plastic boxes on my patio to clean them.
After a lot of experimentation I found OxiClean seems to work best cleaning soft plastic figures.
Here are some of the troops in ZipLoc bags waiting for cleaning.
Troops go into the water along with a scoop of the OxiClean.
The troops were soaked for 12 to 24 hours, sometimes with an extra scoop of OxiClean.
I stirred the figures every few hours to make sure they were all covered with water and cleaner.