I'm gonna have to name names but I'll say right now that I'm stating facts and also that nothing on this site represents the opinion or position of my employer.
I recently noticed that v25 n1 (1991) of the Journal of Composites is missing from the Sage website. We've licensed the whole backfile for this journal and we need an article from it.
I contacted technical support and their response was:
SAGE did not publish JOURNAL OF COMPOSITE MATERIALS in 1991. I checked with our Publishing Technologies Department and the 1991 content you asked for is not available in our archives because the previous publisher did not have all past issues on hand when the title was transferred to SAGE.
I suggest that you look for the back issue at the Periodical Service Company. This company has permission to sell back issues of our journals which are older than 2 years old. They are major reprinters of academic journals and specialize in the supply of back volumes and back issues of out-of-print journals and serials.