did you put the dampener back on correctly? the 8 or so torx screws, i would make sure thats not off its mark and tightened down like you would lug nuts on a wheel.

also see if the vibration goes away when you remove the mechanical fan. if you stored the fan flat then all the fluid in the clutch could have leaked out causing a problem. remove that and see.

one more thing, but prob not the cause. did you bleed the cooling system properly? i'd imagine that air in some of the lines can some problems. (prob not consistent or even that noticeable.)

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