Sticking throttle - Saitek X52 Pro

My Saitek x52 Pro has been working great for a couple of years now but has suddenly developed a problem related to the rudder twist access. I have re-programmed several times but still have the Z rotation indicator flickering between 693 &740 and leaving me with 10 or 15 degrees of right rudder when the stick is centred. Have looked at all I can find on this forum for help, and (carefully) had a look inside the base. All I could see was a small amount of, apparently, lubricant (looks like white Vaseline), which appears to be coming down the main central shaft. There were small deposits on the central wires and some had dripped onto the base plate. Cleaned it up, couldn’t see any sign of dust so didn’t touch anything else. Apparently successful for a short time then reverted to sticking again. This is the first time the base has been removed, and the sytem has been well cared for. Any help or advice would be much appreciated. Asus P6TD Deluxe, Intel i7 975 Extreme, 1GB Asus GTX 285 OC,6GB (3x2GB) Corsair Dominator DDR3, 1TB Samsung HD103SJ, 300GB Western Digital WD3000HLFS, 1000W Corsair CMPSU-1000HXUK, Ultra-120-1366RT eXtreme, Coolermaster RC-1100 V2, Creative Soundblaster X-Fi Titanium with Inspire T6200 speakers, Samsung SH-S223C/BEBE, Akasa AK-ICR-07S 3.5", Windows 7 Professional 64 Bit,TH2Go plus 3 x 22” Samsung Syncmaster P2250’s, Saitek X52 Pro, FS Genesis, UTX-USA, UTX -Europe, My Traffic X, REX2 Overdrive, Plan-G.