I do those things. Normally, I'm pretty competent.... normally... haha. Honestly, the way they looked laying there dirty, closely resembled a type of wax donut, even with layers and some separation.... but alas, it was just a case of dumbassity. I always clean right before reassembly as parts reveal more clues for reassembly. Just an old habit of mine when I'm working on 10 things at once.
