Ara,
with the back of the camera open, advance the camera, the shutter should travel(upwards, I think) & lock in position. If it travels downward when you release the film advance lever there's a problem with the shutter latch. If you can get someone to actually lubricate the thing it'll probably cost $75+
If the shutter has failed mechanically, it could run as high as $175-200.
The problem with lubing the device is access, since a rather complete disassembly is required.
Check with Carol Flutot for repair she's got some sterling recs from other folks here on APUG.