...
Make sure the entire file is loaded; if it's not loaded, there will be a colored bar across the top of the editor with an option to load the entire file.
If there are any foreign language records (i.e. words and phrases like "online resource" aren't in English), export them from the batch to a different file. You will need to search these titles individually in ALEPH and OCLC to find a usable (English language) record.
Use the Extract Selected records tool -- set the display field to 856, and search for |end| -- which is a delimiter that is placed between fields. If it's present, there are two fields in the record.
...