I'm Eileen. Me and my husband have had a well established blue tit box for years and the last 3 years have been a disaster. Both patents coming and going regularly but haven't seen them for 2 days. We checked the box and all 7 babies have died. Last year the parents abandoned the 4 chick's and we had to ring rspca, the year before (2020) all chick's died. Having had success for at lest 8 years previously, we are wondering if there is anything we can do to help them. Do we need a new box? Maybe insulate it a bit? We are running out of ideas. Thanks for any advice. BTW. Box is on the back of the house, facing north and no previous trouble with it.