Well, this is from memory...same problem on '83 944 passenger side.
The exterior part of the door handle has an aluminum piece in it that pushes on the latch to release. This aluminum piece has broke. (clunk) The interior door handle has a long rod that goes to another part of the exterior latch to release it. Thus the interior still works, while the exterior does not.
I think there are two screws/bolts that hold the exterior handle in place. Should be right there at the latch mechanism on the side of the door. After these are removed, the exterior handle will have to be seperated from the rod going to the interior handle. It is a 'snap in' type of connection. Roll the window up, and reach into the door from the inside to grab the rod and pull apart.
Unless you are a machinest, or stubborn, buy a new/used exterior handle and re-install. I was able to re-manufacutre the aluminum piece that broke, but would not recommend it.
Hope this helps.
JM