Tektro RL 340 brake levers cannot find tightening bolt to keep shifter secure
The brake levers are held in place by a metal band that wraps around the bars. The band is tightened with a bolt inside the brake lever. One may see the head of the bolt when pulling the brake lever and looking into the gap between hoods and lever.

A L-shaped hex key should easily reach it. The brake cable might be in the way though. By slackening or usinga ball-head hex key one may adjust that bolt without removing the brake cable.