<span style="font-size: 11pt"><span style="font-family: 'System'">Here's a quote from a Triumph service bulletin. It was written for a TR3 but I believe the design is close enough on the 6 to be of use.</span>
<span style="color: #990000">"GEARSHIFT LEVER CHATTER: The simple corrective measure has been dealt with in a separate Bulletin which seems to have been overlooked by many service shops. Therefore, to briefly recapitulate, remove the gearshift lever knob and boot, remove the top cover bolt and cover together with the inner cover and spring. Slide down over the gearshift lever a fairly heavy piece of rubber or neophrene tube 7/8" long and 5/8" inside diameter. Press it down until it comes in contact with the fulcrum ball. Reassemble and that is all that is necessary. The rubber or neophrene will act as a vibration damper in this position"</span>
<span style="font-family: 'System'">I found rubber heater hose that ID, Cut a bunch & gave them to all my 3 & 4 friends.
FRank </span></span>