I love F1, but I reject the premise that it can be "fixed" in this sense. The best resource I can recommend is Total Competition. The author (I think) was attempting to write some kind of business strategy book, but I read it as a giant interview with Ross Brawn. The title - Total Competition - is very significant. That sums up Ross's perspective as far as the enormous appeal of Formula 1. The drivers compete on track. The pit crews compete for the fastest stops. Team principals play politics with the governing body; they try to squeeze every dime out of investors and parent companies. Drivers politic to get the best rides. They try to torpedo other driver's chances off track just as fervently as they do on track. Every rule is dissected looking for loopholes and workarounds. Total competition. It's like the competitive aspects of society distilled, cranked up to 11, and labeled a sport.
This is why I tell people "it's not racing, it's F1". If you want racing, watch IndyCar. I love IndyCar, but it'll never be F1 for me. IndyCar is essentially some very talented drivers driving the world's fastest rental karts. More times than not, that produces really good racing action. But it just doesn't have the magic and you also have weird stuff like Penske finding advantage by putting millions of R&D into, of all things, dampers. Does space-age damper tech get your blood pumping?!? Anyone? For the purposes of argument, you can replace "IndyCar" with any number of GT3-like series, touring cars, NASCAR, etc. There are bunches of series trying to stay relevant on the basis of closely matched racing action via spec cars, BoP, etc. It can be great fun, but it lacks the magic.
It would be hard to measure this, but over the 70 year history of F1 (and way longer if you count pre-war Grand Prix racing), you wonder what percentage of races and even entire championships were won on some designer's drawing pad. I would have to guess a lot of them, perhaps even a majority.
The idea that Formula 1 exists or is in some way obligated to give us compelling on track driver battles is, I think, a relatively new concept. Formula 1 has indeed given us many classic head to head on track battles over the years, but those battles were very much the tips of much larger icebergs (making those one-track battles all the more special, IMO). On the other hand, Formula 1 has always delivered lots of very full racing. In the days, not so long ago, that most people followed F1 via Autosport articles, I think that was easy to not notice so much. Today, with HD coverage, dozens of camera angles, and spiffy production...if a particular race doesn't generate what's deemed to be a sufficient amount of "action", people are ready to burn the whole thing to the ground for wasting their precious 90-120 minutes that could have been spent on any number other distractions to fill their free time.
So, yeah, that's a really windy way of saying I think this "fixing" notion is a false premise. I think F1, broadly, "is what it is". It's great when it works, it's a little dull when it doesn't. The idea that rules makers have a great deal of control over great vs dull I think is a bit of a false hope.
At the risk of being a hypocrite, I do have a few thoughts on some changes I would advocate for.
1) Ban DRS
2) Allow the teams to more heavily leverage ground effects (the new regs are heading this way)
3) Experimenting with cost caps I think is a worthy exercise. If big money ever starts pouring into motorsport again (don't hold your breath), I'd advocate for removing them.
Anything more radical than this - from sprinklers to bringing back V10s to going to spec cars - is just too extreme. You are going to end up un-F1ing F1. I would rather watch F1 fizzle out naturally than watch some lame imitation with F1 stickers slapped all over it. Just my 2 cents.