1994 Jeep Grand Cherokee Viscous Coupler Additive ?

Folks, I have a 1994 GCL V8 with the AWD and infamous viscous coupler.... just replaced both front axles and rebuilt the drive shaft, and the viscous coupler is still binding, grinding and hopping a wheel when hot on turns that are getting less and less tight. The last thing I want to do right now is replace the viscous coupler. Has any used, or is anyone aware of, an additive that would slicken things up in the transfer case and squeak a little more life out of the vc ?? Thanks in advance -