Hi! Everyone, I am a rookie on audiophile stuffs, just got a Sansui AU5500 integrated amplifier, seems to be working fine but when I hook it up a tuner, the left channel volume could drop a bit all in a sudden but after a while it will go back to normal volume with the right channel, it just happens on tuner selection but it's ok on all Aux, just wonder why? Do I need a dexoit somewhere? Or do I need a recap? Please help! Thanks!