I find in these situation I save a lot of time by dropping the source and creating a new one. If I had SQL coded I copy it ahead of time so as to just paste into the new source component. I can do that almost as fast as going in and trying to tinker with settings.

I also dont like to have SSIS reconfigure invalid colum references automatically. I double click the destination , go in delete all the old ones and select the mappings tab and it will usually reset them on its own.