I am having trouble feeding a narrow tube into the rear differential (via the filler plug) in order to pump out the old gear oil. The tube seems to get blocked about 1/2" after entry, and even a narrow tube can't be bent around the obstruction (the gears I presume) in order to get to the bottom of the housing. I have tried turning the wheels while the car is up in the air to no avail.<p>The car is a 2001 XC70 AWD. I have searched for any info on this issue and haven't been able to find anything. The rest of the fluid changes (tranny, bevel gear) went fine with info from this and other forums.<p>Any words of advice would be much appreciated!