SME 20/2 Finger Lift Hum

On my SME 20/2 fitted with a Lyra Argo i, there is a hum whenever the finger lift is touched, but very quiet otherwise, and importantly, when the record is playing. Has anyone encountered something like this and figured out how to correct it. All possible ground combinations have been tried with no change. Again, the hum is only apparent when the finger lift is touched. Thank you for your help.