you could take the female( blower) coupling off and manually see HOW it 'connects' to the male(tractor) coupling. The 'teeth' should overlap 100%. You can also check how far off of dead nutz center the 2 coupling can be( if any)....
I suspect the make 'cone' isn't going deep enough into the female coupling,or it's binding from being off center.
This is a 'need to see it, hands on ' problem......but since the male side does extend fully and the blower mount is 'fixed' it'll be the actual couplings NOT fully engaging.