Is there a user solution?

Cary Sli80. No left channel in aux 1 or 2. Have switched rca with no change. Aux 1 is turntable 2 is cassette deck. Also on CD, balance will not turn off left channel.
Have you checked the fuses and the tubes in the left channel?
Tested that on CD setting and works fine. Thanks.
Fuses and tubes all ok. Thank you,more suggestions welcome.
Sounds like the balance control is dirty as well as the input selector switch. 
Atmasphere we may be getting somewhere. How difficult to do required cleaning.