How or can I replace the forward window clamp that holds the ends of the cable for operating the operation of the front window ?

OK, I did it by myself. You don't have to buy the whole kit and caboodle from dealer/supplier. Go to junk yard find your car/Focus, take off the panels/hardware/plugs. We are talking about an electric window here. The rear clamp can be replaced without taking the whole assy. out by just loosening the single bolt and then sort of rolling the clamp off the rail carefully. When you do the broken unit you learn the method of removal without worry of breaking what is already broken. The rear clamp can be done with the assy staying in the door, but to ease the repair just go ahed and pull the whole unit out of the door. Its onl;y 4 more bolts. The cable must be removed from the pulleys in order to remove the slider clamp from the rail. Pop the ends out after you have taken the tensionoff the cable. To put the cable back on the carrier, you use the pulley, and lay the cable on it and use the cam that is built into the roller and roll the cable back into place. I paid $15 and did it in a half day, Saved over $100