How to restore DTS permissions after restoring a database on SQL 2000

As part of how we handle our customer support for an enterprise application, we back up our database, I restore it to our server, do some maintenance, create a backup and restore it to my server. This works very well, but I usually have to reset to allow users to this database. But at the moment I have one client that cannot run DTS packages on this server due to the database user being unable to connect to the database. I tried to go through all the possible options and options, and check and recheck the permissions for this user, who is in the dbo role by the way, but nothing works. Does anyone know why I can't connect even though the user has the correct permissions?

Thanks in advance!