Could be a leak from a number of different locations. Also from either the top or the bottom drawer. Dry out bottom tray completely. Leave for a couple of days with bottom drawer open to let air flow. Help it along with a hair dryer if necessary. Once dry the F1 should go away. Then use only top drawer for 2-3 days. If no water comes back then use only bottom drawer for 2-3 days. Once you know which drawer, get repair person back & insist they find the leak & repair it.
Lincoln Appliance NZ, December 2008