Most remedial treatment for gramaphone/phonograph recordings must focus on cleaning and general care. In handling discs, the surface should not be touched, and it must not come into contact with any surface other than the turntable equipment and the protective sleeve. The radical cleaning of discs, a problematic, controversial process, should be limited to gentle dry surface dusting with a soft cloth in the direction of the grooves. (See http://palimpsest.stanford.edu/byauth/st-laurent/care.html for a technical discussion of this subject.)
Basic remedial treatment for audio and video tape is also problematic. Detailed information on treatment can be found at http://www.nml.org/publications/presentations/disasterrecovery/.