Non-standard chain ring bolts?

[badcheese]

I have a good (mid range) but outdated alloy crankset on my High Roller. During my last big ride, I lost two of the five chain ring bolts. It's easy to find chain ring bolts, but they're all the same size, which is about 1mm larger in diameter than the ones I have. They also appear shorter. Mine go through all three chain rings plus two spacers in between the rings. The crank is branded "Alero", and it's at least a couple decades old but has very little wear and seems like decent quality. It seems a shame to throw it away because of a couple missing bolts.

Does anyone have ideas about where I could order such a thing?

Thanks!
BC