Welcome to Pinside.
It would be helpful to know your location. Your English is telling me that you may not be from the U.S. This would be important to know because there are three Big Bens. If you have the U.S. version, you can download the manual and schematic here:
https://www.ipdb.org/search.pl?any=Big+Ben&search=Search+Database&searchtype=quick#228
It is also recommended that you read up here to better understand how EM’s work before we can help you.