I believe I have a 1952 Schwinn Panther. Trying to find the serial numbers but very rusty. Where exactly should I look and will a wire brush help or hurt the bike?
Up until 1952 serial numbers we printed on the Bottom bracket shell, after 1952 they moved them to the rear dropout until 1971 when they were again moved, this time to the head tube beneath the oval badge. Being on the cusp of years i would check both the BB shell and the rear drop out. This information can be found in an informational bulletin released by Schwinn here.
I doubt you will do to much damage with a wire brush, as long as there is not good paint on the frame, which will be scratched from a wire brush. You may also consider using a rust eliminator such as CLR (Calcium Lime and Rust), it could be sprayed on with a spritzer style bottle and rinsed off with alcohol or water. Light brushing along with this may be enough to make out serial numbers.
Once you find it This web site may help you decipher it's model as well as date of production.