Yes...Phil N says it far better than I can.
"On this set, the ion trap is adjusted by manipulating a little metal collar around the neck of the picture tube. A stiff paper sleeve is provided to let you do this without poking instruments down into the narrow space between the picture tube neck and its surrounding metal shield. The paper immediately broke when I tried to move it, however, so I ended up poking a long crooked-neck tweezers in far enough to reach the metal collar.
Sure enough, when I pushed the collar in, the picture immediately grew brighter. Working a bit at a time, I adjusted the trap so that the picture had normal brightness."
From
https://antiqueradio.org/rca16.htm
jr