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Yeah, this is a good starting point. Create a sitemap in GWT with just these pages (it's easier to monitor that way), and re-fetch any specific pages that are critical. You can also build internal links (even temporarily) to kick the crawlers or try promoting some pages via Google+. There's no foolproof method, though - just nudges. This assumes, of course, that you've corrected the canonical tags. If there shouldn't have been a canonical tag at all, then I'd recommend adding a self-referencing canonical (i.e. one pointing to the page itself). A new canonical tag seems to overwrite an old one better than just removing, at least that's my anecdotal observation.