This may be a monumentally stupid question, but I can't find the answer anywhere. On the in-line barrel adjusters near the shifter, which direction tightens the cable?

Just recently I've had issues with it not shifting from the smallest chainring to the middle. Just makes a bit of a racket but never makes the full jump. I'm holding the lever over the entire time, too. Is a slight adjustment to the cable going to help? Or should I start from scratch and reset everything? Shimano's tech doc troubleshooting guide doesn't describe this issue. Nothing has changed recently except riding the thing.

9-speed 105, 5500, triple.

Thanks.