Look here for replacement help:
http://www.airforums.com/forum...highlight=door
Don't be afraid to PM anybody advertising parts in the For sale and wanted Forum. Sometimes parts are the same for a '71 as a '75. Seems to me an access door might be one of those. Don't forget to ask about a key to the lock, I don't know if these can be rekeyed or not.
and after you find your replacement, go here:
http://www.airforums.com/forum...highlight=door
Scroll all the way down for a picture, this is the fix Andy suggests in the first link. My fridge access door needs the modification, but my battery compartment door has a hinge already. I think a PO did that.
Oh, and welcome to the Forums!
