Iteratively remove redundant members until there are none left.
Create a DGML file using a tool for reading the source code, for example
DeepEnds ReadDotNet extract=cohesion output=C:\project\cohesion.dgml C:\project\source.sln
Given that the source is backed up run the redundancy tool to delete the source code, for example,
DeepEnds ReportRedundant deleteUnused=C:\project C:\project\cohesion.dgml
Attempt the normal build process.
Revert those changes which are causing the build to fail due to the detection of false positives. Consider adding some temporary code to force the process into ignoring the code of interest.