Let your G5 iMac breathe, a follow up

Last July, one of our readers working in an Apple maintenance center sent us this warning:

After I had to take care of a few G5 iMacs, I came to notice a detail that might result in a problem.
On the venting circuit for the G5 by heatsink entrance, composed of copper
wings that are distant from each other of a few mm, the dust will aggregate in quantities that may suffice to obturate the heatsink venting circuit.
As the air won't enter as well the fan will turn faster.
It's an issue I dealt with on older G5 iMacs series.

He sent us a pic that illustrates this problem.

The machine is only 6 months old. Once the dust has landed there, fans will have to turn increasingly faster so the CPU might cool well.
The problem is that it's very touchy to dismantle the cache in order to gain access to the heatsink.