trouble with shifter returning to neutral

[Madison Marie]

Hey guys, im new to the site and looking for some help. I have a '05 250 yamaha and put a new lower unit on this year and when you shift from neutral to forward and neutral to revesre it works fine, but when returning back to nuetral from either gear the shifter doesnt "drop" into neutral without playing with it...Any thoughts? i bought the unit from Boats.net and it was supposed to be a brand new unit which it does look like..Thanks