Tinkering the TARDIS with a normal screwdriver because your “sonic” one is too much technology sometimes…
The 12th Doctor is systematically shedding the things he’s used as security blankets throughout his previous incarnations - He’s going back to his ‘roots’ and I think this is something we shouldn’t ignore. The thought I keep coming to is that he’s Weening himself off of the things he’s relied on for so long.
Rather than using the Tardis computers to solve problems, he writes them down on chalkboards. He’s getting more intimate with his thought processes. I don’t know about you, but when I bend myself over a piece of paper and write things out, I’m in a headspace where the gears are -really- turning.
Episode 3, he’s got to think his way out of a situation without the aid of his Sonic Screwdriver and in Episode 4, we’re seeing him separating himself from his dependence on it to do -everything- for him. And we see him pushing Clara into the Tardis to face things by himself. He’s weening himself off her, too.
This Doctor is a lot more actively introspective. I think we’re going to see a lot more of him exploring what makes him Tick and I think we’re going to see more of his past as he tries to decide if he really WANTS to find Gallifrey again, and maybe ‘go home’.