Some issues frequently raised seem to point to maintenance not being done soon enough. eg:
Up and over garage door - mechanism or cables breaking - possibly due to lack of adjustment and lubrication.
Stiff taps - possibly due to washer not getting replaced leading to people being heavy handed to stop it dripping.
Doors catching and needing trimming - possibly due to hinges being loose - or worn.
Drains blocked - does it ever get really hot water put down it?
Toilet won't flush easily - has the water level been checked - if people have to really give it welly then the diaphragm may split.
Just a starter - any other points that a good DIY person should be looking out for to prevent problems occurring. Prevention is cheaper than replacement.