Hi, I've got beige seat belts, and those on the passenger side have, in a few parts, peculiar black blotches on them, almost like a mould. It is correlated on both sides, so appears to have gone through the belt. The stain is present even if I extract a few feet of seat belt, beyond the girth of any normal size person, so I don't think it is spillage, but some contamination from something in the door pillar or in the reel. I've tried soap and a brush, and soaking all day, but it didn't make a jot of difference. There's a thread on here which suggests using Isopropyl alcohol. Now, I have some of this, but aircraft safety restraint doc I found on the internet warns not to get IPA on the webbing, and Honda only recommend soapy water. Is there anything else I can try? Has anyone seen it happen before? I'm also a bit concerned in case it fails its MOT for contamination. For some reason, the inertia reels have a electrical connector, so I imagine there could be a world of warning light pain in swapping a seat belt, if it comes to it.