Always having an eye open for a bargain I was intrigued to see these 54mm semi-flat figures on EBay for only £2 each ! - however the seller pointed out that they had reacted badly to their storage and had damaged paintwork on one side where they had reacted with the paper they had been stored in . I thought at that price I can't be bit - so I ordered them and they arrived promptly .
Lead Rot !!! - I've only come across it a couple of times in 50 years collecting toy soldiers , it can be caused by dampness but it seems to be the contact with the storage material as only one side of each figure is affected .
Also the unprimed basses have been effected . I have been investigating 'lead rot' on the internet and it's rare in modern castings (the two others I've come across were early 70's Minifigs) and luckily not contagious and it can be treated .
On further investigation I think the figures are pure lead - which would help in the rot and when scraping some of the paint off, not undercoated another cause of the rot . I've wire brushed the effected areas with my Dremel back to shinny metal and I think its only started to affect the paintwork as there's hardly any pitting on the metal . I think I might have caught them just in time so I'm giving them a wash in soap and water and letting them dry before undercoating the damaged areas . I'll report back on further progress .