Thank you Keith. I have checked the drain hole, it seems OK. The gutter at the back which accommodates the drain hole is dry. However, every few days ice will build up in the left corner of the gutter, only there. I am having to remove it every 3 days or so. I bought a thermometer and the temperature is usually just outside the range it should be, although milk keeps for 6 days.
Joan Adamson ● 637d