Heat pad not installed when assembling the Playstation 4, should I take it apart again or leave it as it is?

Also consider that you are not necessarily reusable. Make sure this is still healed and sticks as before – if it has glued. If they are torn, you can’t reuse them, but at least that one pad on the pictures still looks intact. You do not break hardware directly, but it can be that the cooling performance is significantly reduced, with the disadvantages that have already been mentioned.

If you want to go safely, buy new ones, but the new ones must not be thinner than the old ones. But you shouldn’t be too much thicker, even if it’s not that bad. Several pads are not an option. To test, you can simply put the new pads between, squeeze the hardware and then see if you see these silicone residues on both sides or even a print in the pad. If so: Not too thin.

Alternatively, if the pads were very thin, you can also take heat-conducting paste, which leads the heat better, but is only suitable for very small distances and is more difficult to apply. In addition, it makes the hardware dirty, that you can clean and harmful it is not (at least as long as it is not electrically conductive, but should stand there), but it looks ugly and a mess when you have used too much.

PS:

Clean the hardware beforehand, it should not be residues on the cooled components and the heat sink. It simply helps cleaning alcohol and a piece of kitchen paper, I have a bottle of 99% isopropanol at home, is generally not wrong to have something at home.