this is a well known problem on b757 a/c caused by lack of lubrication and moisture ingress resulting in corrosion and seizure of the pin and the bronze bushing, it is normally inspected during routine heavy maintenance checks, there is i think a boeing service bullitin on the problem ;sometimes witness marks are painted on the bushing flange and the leg housing to give an indication of migration of the bush, apart from this it not possible to detect the problem without stripping the bogie assy.[the only a/c which i know for a fact have these witness lines are 757 operated by air 2000]