I have a Stanley garage door opener model 3500 51 installed in 1992. I have been using an old Eversafe remote that is broken. I have tried two replacements that should have worked. I consulted Stanley on this and have been told I have an altered frequency and should call a service person to figure out how to program a new remote. I don't know what an altered frequency means. The opener was installed before we bought the house. My husbands remote still works fine. It was the original that came with the opener.