Shin T260 bad vibration and leaving oil residue around engine

I have had my Shindiawa t260 for nearly ten years. Has worked great over the years even after installing the speed feed head. I cut about 2 hours a week on our property with most grass not being overly hard to cut. I have had to replace the clutch once after it broke couple years ago. Last year developed a slight vibration while cutting and it has steadily gotten worse. I have kept the gearcase head greased and removed the shaft greasing it well with Shindiawa grease. The shaft once inserted...

Shin T260 bad vibration and leaving oil residue around engine