when playing in thumb position i seem to have to hook my right hand thumb under the fretboard to give myself something to push against. what i am trying to say is that when playing closer to the scroll the thumb is behind the neck and the fingers are freting notes against this opposing thumb. up in thumb position the thumb is no longer behind the neck so i seem to want to compensate with my right hand. this is kind of OK pizzicato but a complete disaster when bowing. my teacher is classical and sits with back of the bass facing him ala. cello and i have tried it that way and there is no problem anymore. but this position is rubbish for jazz which i mainly play. thoughts?