You're welcome.
The point of troubleshooting is to rule out as many potential variables as possible which would include the intake fans. That's why I asked. Wait... did you say your machine has no intake fans or is that a typo? It's pretty odd to not have an intake fan and even though it's not overheated prior to now, it's still a valid point to check it and keep it clean (if it does have one, that is).
As for your point about using canned air and it possibly drying out your old paste, that's highly doubtful. If it was old and brittle, your use of the air isn't likely to have made any difference on drying it out any further than it already was, so go about carefully cleaning and applying new paste and hope for the best.