Debug an Newsstand app that crashes in appstore

We have had an Newsstand app in appstore for about a year. It worked fine, but after a minor update the app crashes when downloaded from Appstore, both in iOS 8 and in iOS 7. The app works fine in xcode ipad/iphone simulator. The app also works fine as an ad hoc distribution on devices with iOS 6, 7 and 8. There is some conditional code in the source that checks for iOS 5 but not for higher versions, maybe there's the problem. Maybe some settings in target are wrong. Source code and access to our itunes-connect account will be provided for. After debugging and rebuilding we would like you to submit the repaired app as a new version to the Appstore using our itunesconnect account. We also want to receive the debugged source.