I would select one of the warmers with the most product on it. My correspondence in the past with CXG quality control has led me to believe when in doubt, go with what passes. It doesn't mean passing an obvious fail or half or empty. For example, if I look at bananas to judge 50% or 85%, if it is significantly over 50% then I go with 85%.
Do not read so much, look about you and think of what you see there.
Richard Feynman-- letter to Ashok Arora, 4 January 1967, published in Perfectly Reasonable Deviations from the Beaten Track (2005) p. 230