has anyone had the problem i'm having at the minute my 90 developed a vibration , i was told to check my prop shafts ujs and found that one on the front prop had gone so i changed all four while i was at it this seemed to cure the problem, but i used it for the first time today on the motorway and after about 15 miles the vibration returned it seems to be at its worst at 50 mph when accelerating but if i depress the clutch or free wheel there is no vibration pls someone help!!!