The phrase "again tumbling" is correct and usable in written English.
It can be used to describe a repeated action of falling or rolling, often in a figurative sense.
Example: "After a brief moment of stability, she found herself again tumbling into the chaos of her thoughts."
Alternatives: "falling once more" or "rolling again".
There was a point in the season when Saracens wondered when they would win again, tumbling to defeat in the Premiership, Europe and the Anglo-Welsh Cup.
But after defeating the Miami Heat Saturday night for the third win in 12 games, Washington avoided again tumbling into the national news cycle as the NBA's most dysfunctional team.
This month, the market sank again, tumbling below 11,000 as concerns about the financial health of the nation's two largest mortgage finance companies, Fannie Mae and Freddie Mac, gripped markets around the world.
This time the anger again tumbled out fast, a huge contrast to the girlish giggle that Williams affects in her mandatory interviews after matches.
Coffee prices again tumbled on world markets.
The tears once again tumbled down my face, but this time they were full of happiness.
And then scene deleted you wake up, and roll over, and put the TV on, and you realize you have once again tumbled off the wagon and been trampled by its self-righteous wheels.
[C6.] Shares Again Tumble After Rally The Dow Jones industrial average closed down 38 points, at 7,717.61.
A great Tumblr post is reblogged again and again; it tumbles across continents and generations.
Another, Hannah Gavios, above, had to learn to walk again after tumbling from a cliff in Thailand and being sexually assaulted while she lay helpless.
The film opens with the image of the second World Trade Center tower being hit by a plane, and returns to the attack, with the towers in flames and then tumbling, again and again.
