Can you post up the FD number Andy. Most of these have had the mods done already . There are a couple of other things to check .
Is the evaporator frozen or are they getting ice in the base of the freezer compartment and on the RHS ? I have had a few where the white insulating part that the deforst heater sits in has split adjacent to the drain hole area , allowing deforst water to run into the freezer compartment rather than the drain hole. Always worth checking the defrost heater too.
The mod consists of a new module and a metal ‘blanket’ that sits above the evaporator . Does this one have this fitted yet ?