So, turns out I had a faulty cooling fan (amongst a bunch of other things I went over, disassembling my hot end/extruder and cleaning, checking alignment, etc.). Turns out my bed is just fine and mesh leveling works as it should. Lots of other little adjustments, fixes and the aforementioned cooling fan and I'm back in business.
Thanks so much everybody! I love my machines with Duets running them. The great community of knowledgeable and generous geniuses make my love of the Duet even stronger and more enduring.
Rock on!
Chris