I guess you mean the COMPOSITE output (RCA jack).
Sounds like the output jack may have come loose from the circuit board.
If the unit us under warranty, get it to a Canon repair shop.
If its out of warranty, see if there are any good electronic repair folks in your area.
Tell them you think its a loose jack on the circuit board and see what they estimate to open the camera re-solder it.
However, the following can save you a lot of money over having the camcorder serviced.
Have you tried using the S-Video output to see if this works?
(Feed it to a TV/monitor that has an S-video input.)
If that jack works, you CAN connect it to a standard composite monitor (one that does not have an S-Video input) by using an “S-video to Composite Adapter”.
This passive device does nothing more than “parallel” (combine) the video and the color outputs from the “S” jack and feed them together to a single RCA or BNC plug that will fit into a standard monitor.