I would perform the usual 6 month cleaning (the one where you use CANNED AIR) on the vents and if this is many years old it's time to replace the usual compound.

Don't let your diagnosis blind you to the usual. We see such a lot in the shop as folk "prove" it's not this or that. We nod and do the cleaning and compound and you don't want to know how often that works.

I can't tell which cord you are asking about. But the cable from the mainboard to the LCD is a suspect but not high on my list.