Rumble fuse –
Check one of the fuses near where your fan is plugged into the mainboard. Don't know about the PAL units, but the U.S. NTSC ones are around that area. Should be a little black box with a number on top of it. More than likely a "S7", but could be marked "30".
If anyone knows this is wrong, please feel free to correct me on this one. I'm not familiar with PAL consoles.
Hope it helps!
Unfortunately, common sense isn't really that common after all!!!