If that's the case, then it may have been damaged in the last ~2 years. One of the VCRs or cameras it's gone through may be scratching or warping the plastic/poly tape materials.
Of course, people's memory's aren't even remotely close to as good as they think they are. It's one reason I write everything down. Bad memory is why there's so many myths on the Internet; for example, "my data disappeared from my DVD" -- usually just somebody remembering wrong (or having never tested it, therefore no basis on which to make the current claim.)
So if the memory is accurate, damage. (It may not be the tape, maybe just the VCR?)
If memory is bad, then it could be signal issue as easily as tape/mechanics issue.
I know how aggravating this is. I feel for you.