Solvents for removing very old masking tape from front panels?

The goo doesn't ruin the type cylinder. It's the lack of rubber pad that does. The part is a little rubber pad on the face of the print hammer. When the machine prints a character, this hammer strikes the front side of the type cylinder and knocks it onto the ribbon/paper so that the caracter on the back side is printed. The rubber pad prvents metall-on-metal contact which would damage the characters that were directly hit by the hammer. So, if the pad has turned to goo, it no loger performs this function. The metal of the stud that holds this pad hits the type cylider and damages the character forms on the opposite side to those being printed. I _did_ haev some brand new replacements for this pad, genuine Teletype parts. But they have turend to goo too over the years. -tony