"more guarantee" is correct and usable in written English.
You would typically use it to signify a greater level of assurance. For example, "We have more guarantee of success if we make a detailed plan ahead of time."
There are few things more guaranteed to bring together a community than gossip.
Our data suggests there is also no programme more guaranteed to fail".
Her critics, she said, wanted "a faster, more guaranteed route," like the order to lift test scores annually.
They were talking through the options for a "more guaranteed remuneration package at some point in the future".
If county and city officials are that mistrustful of their constituents, they need to find a more guaranteed source of financing, even if it means collecting more taxes.
Nor are there any more guaranteed opportunities for news or campaign events to intervene to alter the dynamics of the campaign, at least not at the national level.
The Red Sox promised Smoltz more guaranteed money at $5.5 million, which was crucial because he is recovering from major shoulder surgery and will turn 42 in May.
Even Cliff Lee, who turned down more guaranteed money from the Yankees to sign with Philadelphia last winter, wound up with the highest average annual salary for a pitcher.
The success of the magazine, seemingly inevitable in retrospect, was no more guaranteed than anything else the pair has impulsively undertaken since — including Mr. Slotover said, Frieze New York.
A university official with knowledge of the contract said that despite the extension through 2015, the university's financial obligation is identical to the prior contract, so the university extended Gonzalez's contract without offering him any more guaranteed money.
No article is more guaranteed to elicit an outraged response from readers than one which dares to suggest that these islands are really not such a terrible place to live.
