Thanks for the replies. It seems to me that two factors emerge as
important (both related to air circulation)

1) Move the air inside the fridge so that the heat is evenly stripped.

2) Replace the heated air around the cooling fins on the fridge back
with new (cooler) air so that the heat is dissipated.

So fans seem to be an important issue.

One more question. Exactly how does the thermostat get info on the
interior temp? Seems like mine may be slow in getting the signal to
restart the cooling cycle after the initial cooling has expired.

Ian