If you have ruled out the video card and are sure it's the cable, it can be replaced but I would not say it's a job for the timid. You will need to get your hands on a VGA cable and not just an extension. Perhaps you can find one made for a CRT that has a removable cable and this will be more heavy duty than cheap extenders. You will need to unplug the power and VGA cables and then remove the cover from the rear side of the monitor. Usually these are attached by screws at the corners. You must use EXTREME CAUTION while inside the CRT. You should especially avoid touching the glass envelope and thick wire that attaches to it which goes into the rubber boot on it. This wire carries very high voltage while the CRT is on and charges the envelope which becomes like a large storage capacitor for a time. They usually bleed off when power is disconnected but sometimes hold a good charge for a while. There is a way to "assist" the discharge but I will not go into that. Just be carefull! Now, you must cut one end off your VGA cable. They should both be "male" so it should not make a difference which one. You will need to trim off the outer sheath a bit and strip each of the wires in the cable. Next, you need a DVM or some kind of continuity tester as you must be able to match each pin on the connector to one of the wires. You may also encounter a braided sheath than will need to be dealt with. The wires will have a color code so match each to a pin on the VGAs "D" connector. Draw a nice picture to help. Now you must do the same with your bad cable. you will need to cut each of it's leads with the monitors case but leave some so you can match the colors. You will need the DVM/Ohmmeter to, again, match pins to wires and then determine which wire of each cable matches to the pins of the other. If your cable is bad, you might find one wire that has no matching pin and this would likely be the bad one. Once you have done all this you can solder in the new cable. It may be easiest just to cut and splice each wire using shrink tubing as an insulator. As best you can, try to preserve the strain relief device which surrounds your cable as it enters the case. This is there so you don't break wires accidently. If all goes well and every wire is properly soldered to the right connection, your monitor should work. I have done this myself but I have training in electronic circuit repair. If you find this to be uncomfortable to you, you might know someone who has done TV repair and such and has the technical skills to do it properly and safely. That's all I can offer but since you asked...that's how. Good luck.