I did a youtube search a couple summers back and that fellow explained how to calibrate line counter reels in a way even I could grasp easily. One other tip I might add is to measure out 40' and mark it with a felt tip pen, color the line @ 1' so its easy to see. That way you can use that mark to help keep the bait at the correct depth. When the mark touches the water and the number on the counter, add or subtract that amount of line to keep the bait were you want it.
You know me, I'm always ready for a road trip. Chip Newest member of Traveling Team Overalls