Keep sending them your weekly team mail. You might want to send them an individual email stating that you are here to help them, but I would leave it at that. I get plenty of PSAs who earn 1000 VP the first day and are never heard from again. You can't let that bother you too much.
As Gery says, work with the workers. Keep signing up more PSAs, sooner or later you will get at least five who will duplicate what you do.
