Sometimes that seal around the shifter gets a slight bit crooked when you pull the cover off and on ..
Make sure the seal is square and maybe a little sumpin-sumpin on the seal so its lubed where it rides in the shaft.
I don't think the tolerance are that close that gasket missing would make it bind.. (but.. maybe..??)

Build it the way you want it ..... then learn how to ride it like you own it..
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