I smell extended Overvoltage situations too!

This, plus the possibility of maybe the Caps are Polarized Electrolytics, would be sure to cause ruptures.

Are the Caps marked with any Polarity identifiers (aka "+" and / or "-", or listed as X00 VDC).

Polarized Caps continuously subjected to AC would fail (unless there's something I do not know of new Caps???). The higher the Hz, the easier to fail.

Scott35 S.E.T.

Scott " 35 " Thompson
Just Say NO To Green Eggs And Ham!