A site visitor recently asked if we could replace his old Marksman remote transmitter with FCC ID H5OT12. That remote is no longer made, but it can be replaced by a newer Marksman remote with FCC ID H5OT21. You can see both remotes at the following link:
Marksman remotes
The customer also asked about programming his system to accept the new remote. Programming Magnadyne alarm systems is accomplished through the valet (shut-off) switch. If you do not have a working valet switch, Remotes Unlimited can provide that with the replacement transmitter. It is also helpful to have a working siren for the system because the audible chirps provide feedback during the programming process for a replacement transmitter.