Good Afternoon, glynnw:
From the Tortuga mini ePot v3 web page...
'About LDR impedance and calibration
Due to its small size, the Mini is not capable of calibrating its own LDR attenuation module. Therefore is you need an LDR attenuation module with a difference impedance level or to replace a bad module you will need to purchase LDR modules from Tortuga Audio. Alternatively, if you also own an ePot.V3 Max you can use any Max to recalibrate any LDR module at whatever impedance level you wish. If you send in your existing V3 LDR attenuation module, we will recalibrate your module for you for a $5 fee plus return shipping.
For more general information, please refer to this link to read more about LDRs, their impedance and their calibration.'
Hope tortugaranger (Morton) doesn't mind my quoting a subsection of the web page.
glynnw, were you a beta tester or something? My understanding is that the min ePot v3 has only been recently introduced and in production-wise. Reason is I have one on the way and if what you indicate about the drift would cause one to be concerned if they do not have the requisite Max but can opt to send it back to have it re-calibrated.