My own favourite view of the Force is that what is called "the Light Side" is the Force in its natural state, and the Dark Side is a corruption. But not some external corruption, in a quasi-Manichaean way, but rather one produced by us. All objects bathed in light cast a shadow, and all sapient beings immersed in the Force likewise cast a shadow. It's the manifestation of their negative impulses in the Force, and this creates the darkness. To reject those evil impulses is to choose the Light; to embrace them is to choose the Dark.
Just as in real life, choices tend to be self-reinforcing. As Aristotle points out: virtue is a habit, because our character is formed by what we repeatedly commit to doing. In this same way, evil is also a habit. Of course, few people are fully evil or fully good. We all have redeeming qualities; and we all have flaws. There is some darkness in even the brightest, and some brightness in evel the darkest of souls. This is what the Taijitu (Yin-Yang symbol) represents in Taoism: the notion that to be one thing, we have to accept that the opposite exists within us as well. That leads to inner harmony.
(We may note that Anakin never grasps this, and never faces his inner darkness, during the prequel trilogy. His only way to deal with it is to deny it. It ends up consuming him.)
But my point is: "balance" is inner harmony. It's not "mingling black and white to get grey". That's chaos. That's the opposite of harmony. This is why I'm not a fan of the "balance is equal Light and Dark" idea, and certainly not of "both Jedi and Sith are wrong, there's some grey balance in between" meme.
Since our choices are self-reinforcing, the idea of using Dark for the purposes of Light simply won't end well. We aren't defined by our intentions, but by what we actually do. Do evil things with good intent, and you're still doing evil things. See; Revan, Darth. (The game mechanics lead to an illusion of achievable balance, but the actual story shows us where that leads.)
The true balance of the Force is to embrace the Light, while recognising the Dark that exists within you. By facing it, you prevent it from controlling you. It's not that you can destroy the Dark. It's that you find harmony and thereby gain self-mastery. Then, the Dark has no more power over you.
In reverse, someone in the throes of the Dark can face the Light that still exists, even within himself. Facing it allows you to overcome the Dark, because even the smallest flame can drive out any darkness. Stover makes this explicit in his novelisation of RotS. (Note that Stover is into Taoism and knows what he's talking about.) This is what ultimately happens at the conclusion of RotJ: Luke's hope, compassion and foregiveness are enough to bring Anakin to find that little spark of Light within himself, and it saves him.
That's the restoration of the balance. And because microcosm and macrocosm reflect one another; to save one life is to save the world entire. Anakin's redemption also brings about the defeat of the evil Palpatine, thus restoring balance to the galaxy at large. But at its core, it's not about the Force-as-an-external-power. The restoration of balance is Anakin making a choice.
Salvation is personal. In that, Star Wars reveals itself as actually being profoundly Christian. That should surprise no-one, because it's a poduct of Western culture, and the West is always a Christian society at the root (even if not explicitly so). This also suggests that metaphisically, Christian salvation and Taoist harmony (and Aristotelian eudaimonia, for that matter) are all telling us the same thing. And Star Wars is reiterating it, in its own way:
You bring balance to the Force by bringing balance to yourself.