@eiliscoleman While it's not impossible that updating the firmware to the 2.0.8 software baseline could show an improvement, the 2.1.x hardware is fundamentally better. For that reason, I think you'll have the best possible experience from Air Quality Egg by sending those four units back to us for update operations.
I sincerely apologize that your previous email slipped through the support inbox, I did a search and found your previous email, marked read, but with no reply. Please give us another try via support at wickeddevice dot com and we'll make arrangements with you.
We would at a minimum ask you to pay the round trip shipping costs, and probably a modest service fee to cover our handling time and replacement hardware. Lets negotiate those details offline.