Why did mine fail?
Pick the symptom. Each answer comes straight from the converter rule base — and filing testimony about your bake is what sharpens the next answer.
Gummy texture Fell apart / crumbly Dense / heavy Dry Sank in the middle Bland Spread too much Gritty
Sank in the middle
Underbaked center is the usual cause (bake to the long end, 210°F internal on cakes). King Arthur's own structural fix for repeatedly sagging layer cakes: bake it as a Bundt.
Run your recipe through the converter — it applies these rules automatically.