My initial guess would be that the throwout bearing and/or pilot bearing are going bad. Inspecting the clutch components isn't exactly easy, as I'm sure you know, but I'm not sure of another way to adequately diagnose the problem without doing so. Hopefully someone else can chime in who has had this sort of problem as well. Good Luck.
Try bleeding the clutch hydraulic system first and check for any leaks around your slave cylinder and or clutch master. Your pressure plate may not be completely disengaging which is what might be causing your vibration. There is a special procedure for this so make sure your read your bently manual on it. At least checking these things out first will rule them out and the best part is you don***8217;t have to drop your tranny. But if these parts check out and you still have the vibration after you bleed the system out then it could very well be a bad pilot or throw out bearing.
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