New iMac Adhesive Foam tape

I really wish iFixit would add a panel to end of all the 2012 and 2013 iMacs about needing foam tape to reseal the display. If you go strictly on the information provided you will get to the end and not have any tape on hand and have to scramble to find some. For example the hard drive replacement has 34 steps. A 35 step about how/where to apply the tape would be nice. The key is what is the best way to remove the tape that's there already or maybe someone may not even be aware that the old tape needs to come off first.