This is quite common on the F1. I think the actual handle can break and/or the mounting for it has rusted out.
I've not had it happen to me but there are some write ups on here for fixing problems. The search box will hopefully find them for you.
I would imagine the door card will need to come off, so if the wires to the handle have come loose, you'll need to emulate the handle micro switch by connecting wires to open the door to get the card off.