“The Path <local path> is already mapped in workspace <machine name [old tfs server]>”
If so, check this URL:
http://blogs.msdn.com/b/buckh/archive/2006/09/12/path-is-already-mapped-in-workspace.aspx
I’ve been able to fix it writing this command from the “Developer Command Prompt for VS2013”:
tf workspaces /remove:*