sounds like it may be at least 'door rot' - there's a plate inside the door for the lower hinge that has 3 weld-nuts on it - that plate commonly rots enuff to break free, or 1, 2, 3 of the nuts come free .... you should be able to get an idea of condition by removing the little cover on the inside of the door where the hinge bolts are, and get a better look at what's moving
you should be able to find hinge pins the right size in the generic Help! rack at the local, or the vendors carry them ... not too hard a job
Bill
