Jun.23 - Mercedes has now solved its early-season tyre problems.
"The hard work paid off," the Briton told Germany's Auto Bild.
He also played down recent speculation that Mercedes' struggle was amplified by an alleged advantage gained by Sebastian Vettel over the winter, as the Ferrari driver participated heavily in Pirelli's 2017 test programme.
"We would have liked more top drivers as committed to work as Sebastian was (to join him)," Hembery said.
"He gave us important feedback from morning to night, pushing us in the direction the drivers wanted, and we have to thank him because it makes a difference whether an inexperienced driver or one of the best tests tyres," he added.
Still, he thinks any advantage Vettel got was fleeting.
"If there was an advantage, it was at the very first winter test this year," said Hembery.
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