Rear Sunshade not Retracting

[bbrewer]

I have a 94 S500, and have a problem with the rear sunshade.
The motor and linkages work fine, and it comes up perfectly. The problem occurs when I try to lower it.
The shade material itself only grudgingly retracts, or rolls itself up.
I can usually get it to coil-up correctly only if I try to go up-and-down with it 3-5 times.
It there an easy way to lubricate the roller ends?? I presume it works pretty much like a house window pull-down roller shade...
Thanks.

Barry