For removing the tar, I got some compressed air from a computer store and shot it out at the tar with the can upside-down.

This makes a freezing gas come out and it quickly freezes the tar so you can chip it off. This is better than the dry-ice, which I also tried. The dry-ice is fine, but it's hard to position it on all the slants and corners and such. With the compressed air, you can shoot it exactly where you want it.

Also cans of compressed air are a little easier to get.