From Avid's Facebook page
Kurt Wenger - Just take apart the gearbox, pull the kit topshaft and spacer out. Put in the new topshaft and the blue tube goes on the outside now. Then add the motor plate spacer and motor plate with the longer screws to hold it on. Make sure and keep the washers under the screw head.
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Seems the AE topshaft spacer isn't needed, cause Kurt didn't say to put the spacer on the Avid topshaft.