I have never worked on one of these BUT, if I understand your description correctly, it might be a good idea to slide a piece of heat-shrink over the screwdriver shaft and shrink it to reduce the risk of shock or damage.
Why not contact Carvin or go to Carvin's user forum
http://www.carvinmuseum.com/index.shtml to get better instructions for proper adjustment technique.
HEY! those are both banner suggestions. I like the heat shrink one...of course i'll double up on it cause im chicken {censored} about getting zapped.
thanks! :thu: