Are you just replacing the skirt or looking at rebuilding the entire bumper? Rebuilding and in the same process of replacing the skirt (a $1.00 part) with a new bumper body only takes 30 minutes and makes your game come to life. While you are there replace the coil sleeve (another very cheap part).

So it you are looking at replacing the skirt, do a rebuild while you have the bumper apart 

On how to replace see:  http://www.pinrepair.com/em/index2.htm#pops