Cleaning up a gif file

Hi all,

I found a white model of a M-3 Grant tank.

It is 1:100 scale and I will rescale it to 1:72 scale. However, the lines on the drawing are pretty rough and would likely be slightly too thick after scaling. How does one go about cleaning the drawing up? Is there some preferred method or am I just going to rescale and trace a new image over the old?

Thanks in advance for your help.

John

PS. I am not allowed to post the URL to the model since I am a new poster.