Fairly new spinnaker pole - one side won't close on its own. Can I repair this myself?

My spinnaker pole is about a year old.  For some reason one side won't close on its own.  I end up accidentally releasing my spin sheet when trying to attach the pole. 
 
I've tried WD-40 but it is not working.  What else can I try?
 
Thanks!
 
Tracy

I had this happen to a new tapered pole.  No form of lubrication tried resulted in substantial or permanent solution.  Careful inspection revealed that the casting was deformed.  Must have been over torqued at the mast end one day?  Nor sure about the casue of it.  If lubrication doesn't work, maybe you have the same thing. 
I was able to reform mine back in to sooth operation with a very heavy screw driver blade and banch vice revesing the torque that must have occured in operation on board.  Being genlte and trying a littel at a time and testing.  It has worked fine since then (3 years).
The screw driver blade was definitely sub-optimal.  If you could get a piece of bar stock closer to the width of the slot and long engouh to get in a vice, that would work better.
Rowan

Some lubricants can cause plastic to swell.  This may be the root cause of the problem.  many of the newer pole end fittings are plastic, though hard to say what type.
Here is some info regarding compatability of plastic and lubricants:
http://support.newgatesimms.com/lubricant-and-plastic-compatibility-issues/
The best bet may be to avoid lubricants altogether and just use water.  
Hard to say if the pole end can be saved once it has swelled.
-John