In 1964, the incredible Hulk received a reprieve from his 1½-year hiatus following the cancellation of his first, short-lived title, and returned to comics as a split-feature in the Tales To Astonish book, which currently starred Giant-Man. To get the ball rolling, the final full-sized Giant-Man story had the "man of many sizes" battling the Hulk--after which, the following issue pulled out all the stops to throw a spotlight on the addition of the Hulk to the mag. The marketing blitz included an off-beat splash page for the Hulk's tale that had the reader wondering if the character had gone through a major refit and was now going to blend in much better with the rest of "mighty Marvel," no longer the gruesome outsider looking in.
Quite the splash the splash page has made, already delivering a Stan Lee sales pitch that's way over the top. "Let's forget," it seems to be imploring, "that the Hulk had already 'been awarded his own series,' in early 1963"--a series that never caught on and was abandoned after six issues. "Try not to dwell on the fact," it urges, "that 'Thunderbolt' Ross and his daughter, Betty, are about as far from being the Hulk's--or anyone's--'fun-loving friends' as you could get." As for the connection between the Hulk's personality and status-seekers, I can't even begin to speculate on that one--but I could ask in response, "Does the Hulk seem like the type who would be concerned with competing for status among the rest of society's status-seekers?"
Despite how the page attempts to convince us otherwise, the issue's Hulk story doesn't substantially deviate from or otherwise tweak the Hulk's circumstances from where the Incredible Hulk series left off. Banner has remained as a scientist/researcher under the command of Ross, highly reputed as a brilliant inventor and physicist but a "weakling" in Ross's eyes whom he barely tolerates. Ross remains a gruff, hard-edged career soldier who demands results from Banner but otherwise wants little to do with him. Betty is still romantically drawn to Banner, which irks her father to no end. And the Hulk continues to remain a mystery, with Banner becoming more concerned by the day that his identity as the dangerous brute will be discovered. It all amounts to Incredible Hulk 1.5, though Lee appears to insist otherwise.
That said, Lee does attempt to bring coherence to at least one aspect of the Hulk that, even in a mere six issues, had evolved to the point of confusion: the trigger for the Hulk's transformations from Banner and back again. In the beginning, the cause was nicely settled on in its simplicity, and perfectly appropriate in keeping with the feeling of mysterious danger that the Hulk series wanted to convey.
The problem with a dawn/dusk cycle was presumably that it would strictly limit the Hulk's activities and encounters to nighttime, thus also limiting his plots. In his third issue, that limitation was remedied due to a freak accident in a space/Earth communications linkup, that not only allowed the Hulk to exist in daylight...
...but also resulted in a peculiar side-effect that came with its own limitations.
While we can agree that just about every teenager wants a Hulk of his own to command, Rick's new control over the Hulk only lasted as long as he stayed awake, so the clock was already running on how long this new change to the Hulk's condition could last. There's also the fact that, as little personality as the Hulk exhibited beforehand, he now had practically none to speak of, so long as Rick stayed in control.
It doesn't take long for Rick to attempt to change the Hulk back to Banner with a gamma ray machine that Banner has at his lab located in a hidden cave. (One of the constants in these early stories is that Banner appeared to have a lot of forgotten inventions lying around--such as the T-gun plans, for instance--that could be used or misused by the military or spies. Banner seems to have had quite a lot of spare time, in spite of being worked like a dog by Ross.) The machine works; but Banner further modifies it in the hope of being able to trigger his Hulk transformations while also retaining his own mind. He turns out to be half right, with the result of the Hulk thinking and acting with a more canny and aggressive intelligence than he started out with--but lacking Banner's influence, at least on a conscious level.
As a result, from this point on Banner depends on the modified gamma machine for transforming to and from the Hulk.
(Sure, I know what you're thinking: "Gee, Doc, if you want to stop transforming into the Hulk, you might consider unplugging that gamma-ray machine you're always stepping in front of!")
As Rick notes by the end of the first Hulk series, this method of initiating the transformations is by no means stable, with debilitating effects that had already been accompanied by unexpected results during the change. That storyline, however, is abandoned when the Hulk begins his feature in the TTA book, as Lee addresses the first order of business: settling on a definitive reason for the Hulk's transformations.
If you were paying close attention to Banner's explanation, you've seen how Lee's line of thinking has looped back on itself and ended up making little sense. The reason for the change to the Hulk is plausible enough, and ties in with the Hulk as he was written when he was again granted a solo title and for hundreds of issues thereafter; but, confusingly, the same reasoning is also used for changing the Hulk back to Banner.
As an example, let's skip to a scene where a nasty spy has hijacked another of Banner's inventions--an indestructible robot capable of surviving atomic explosions. The news agitates Banner to the point of transforming to the Hulk and confronting the robot--but according to Lee's new explanation, if the Hulk's state of rage elevates his heartbeat and pulse beyond a certain point, the heightened state of anger will trigger his transformation back to Banner, the very same set of circumstances which transformed him into the Hulk in the first place. Does that make sense? In effect, we have a Hulk hamstrung by a circuit breaker, one that kicks in when he becomes angrier.
And so this issue leaves the Hulk with little to show for his reboot, the mood nowhere near as light and carefree as page one assured us of. Banner seems directionless as a character; Ross comes across as two-dimensional; Betty would be more at home in Stepford; and the Hulk looms on the cover but otherwise fails to impress. Nor is the story's final scene able to put a happy face on things, all but suggesting that a "soap opera" is a great selling point for the next issue.
It takes a few more issues, but, for what it's worth, Lee finally corrects his lapse in logic and has the Hulk's transformation back to Banner occur under more reasonable circumstances--this time, taking place when his anger recedes, and he's in a state of calm or lack of stress. The adjustment was made without explanation or regard for the Hulk's prior condition, but of course proved to be more workable as a long-term development that would involve Banner more directly in the Hulk's life, and vice versa.