[Maarten]

There's two things that sort of resemble a clip, the first a strain relief, the second a connector. The white roundish part that attaches the cable to the bottom of the case for strain relief, isn't part of the cable. You can just unclip it and remove the cable from it. Then use a terminal block to attach the new cable to the old stub which is still attached to the connector. Use the strain relief thingy to reattach the new cable to the case. The terminal block will sit happily above the connector being propped up by the wires. You can unplug the connector by pinching the lever on the side and pulling it, if that makes it easier to strip the wires.