When you get the pedal cluster out of the tunnel, reach inside the tunnel and follow the end of the cable back to the tube it runs in. It should be welded to a small bracket attached to the inside of the tunnel. Grab the end of the tube and see if it moves around in any direction. If it does not move at all, that’s good. If it moves at all, it will need to be re-welded. That may require a small opening on the passenger side of the tunnel to gain access to the tube and bracket to weld them back together.
Now go back to the other end of the cable where it exits the frame. It should also be welded to the frame right where it exits. If it is loose at all it will have to be re-welded to the frame or it’s mounting bracket. For that it might be easier to use the David Stroud trick, but I just tack-welded mine in a couple of spots and it has been fine since.