I was using my newly acquired FS80 (newer model) to edge mulch beds. After just a few minutes, my throttle hand went totally numb. Within 30 seconds of returning to normal trimming position, the feeling came back. This occurred several times in a row. I then had some heavy trimming and went to full throttle--same problem with hand going numb. Swithched to the Kaw KGT27A, no problems for the rest of the day. Today, I switched the gearbox and drive shaft with an older Stihl I have--same problem with numbness--apparently due to viberation. Any fixs for this problem? I love the way the FS80 runs and hate to not have it in service!!