JVC Model NO. AV-2672S audio out

i have a JVC Model NO. AV-2672S from September 1992. The audio is out even though the sound is turned all the way up,the picture is fine and sometimes when we turn it on the sound starts at 50 and goes all the way down to zero and sticks there which causes all of the buttons on the TV and the remote to stop working, as in we cant even turn it off without unplugging it.There is also a high frequency noise that has beats every few seconds that you don't hear unless you put your ear really close to the speaker.Can anyone tell me whats wrong with it??