Simple Tutorial:
Image > Adjustments > Auto Color (1/2 of the time this will remove the right amount of yellow)
or
Image > Adjustments > Color Balance (a slight adjustment towards Blue, Magenta and Cyan can remove just the right amount of yellow)
hope this helps.

Good to know I am making a USAgent too and most of my pics show a black center. As I am doing the exact same fig so I wanted to make sure. I won't post mine I already posted like 3 the eagle shield is his 3rd (well now it would be 6th) shield. 1st black buckler & apparentlyhis 2nd Black buckler w/star, followed bt photonic Buckler from Tony Stark as he had throw his shield in to a body of water (not sure if it is in LA or NY) he then recieved 2 shield that where part metal part photonic while working for STARS both where crusader shields w eagles on the top and energy out of the bottom.(only difference between them was color gold photons and blue photons) Then after leaving STARS he recieved the Eagle Round shield in Invaders and then 2 Starshields with the names of fallen soldiers on the front. His costume changed with most of the shields. Anyhow great work on the figure very nice

thanks!
yes, I'm using photoshop to apply the logo, but that's the only thing I know how to do with the program. I need to read up on some PS tutorials.
Thanks! I found the shield to be different in a lot of the source material I looked at. Some had them with a black center, some with a star, some shaped like an eagle......I used this pic for reference, mostly :

Awesome custom I love it. One question I thought USAgents buckler(shield) was all black in the center as in it has no star? I could be wrong but just a question. Other wise very nice

Figure looks good. A question though: are you using Photoshoppe to put in your logo? If so, you know you can remove some of that residual yellow from the lighting right?