This is what the secondary hull and nacelles looked like in the crate when it arrived at the Smithsonian from Paramount:
When assembled, she looked like this. The Bussard domes and sensor dish were missing, so they fabricated new ones.
They sealed up the opening in the port side of the secondary hull where the wires used to enter, touched it up a bit, and put in some new lights, then she was strung up outside the Life In The Universe exhibit...
The first refurbishment was pretty minimal. What you see on display now in the Enterprise
's permanent location in the gift shop is the result of the second refurbishment the model has gotten since the one pictured above.