I agree that you need to try a lubricant but I wouldn't recommend any oil based lubricant in that area. I would try silicone spray. It will flow until the carrier evaporates and it won't attract & hold dirt that turns to gunk (there's a highly technical term for ya) like WD 40 and the others will.

Save a life, adopt a senior shelter pet.
The three main causes of blindness: Cataracts, Politics, Religion.
Name your dog Naked so you can walk Naked in the park.