would it help if you saw a pic of the diff?
Sure.
Generally when you open a tint file you'll see one of two things. If the file is entirely black that equates in game to that particular item not being tintable. If you see red, blue and green areas. Each of these areas equates to an area on the item that can be tinted. If you're having trouble seeing what correlates to what grab a copy of the tint and paste it on top of the diff then change the opacity to about 40. Then you'll be able to see which sections will change what. You'll want to make sure you use the eye dropper tool to get the exact red, blue or green that they're using if you're going to change a section.