Its been a long time since there was activity on this subject, but it looks like the original query was never answered. My throttle control slowly slips back from 1400 RPM to around 1200 RPM over a short period of time and its likely to drive me insane anytime soon. I am struggling to work out what tools I need to adjust the friction setting on the Vetus controller. There is a hole to the right of the lever with a plastic bung which the manual says is the adjuster for the friction control, but for the life of me I cannot see anything inside this hole. I have tried screw drivers, cross head and flat without success. Can anybody help. Does this hole really conceal an adjuster?