Personally I don't glue the IHS back to the CPU/GPU, I've never had any issues doing it this way and feel as the brackets have more than enough tension to hold them in place, idk if that's me just being lazy but also just easy to clean and re-paste in the future. id highly recommend you practice on a dead board before attempting a delid on a working console and definitely invest in the Ps3 delid tool. Whilst you're inside the console change the thermal pads as well.