Originally Posted by ccrydr
Is the issue the 8 pin vs 6 pin and this bridges that?
This is exactly the problem it corrects. The newer decks use the 8 pin configuration while the older remotes use the 6 pin. The CCUMRA1 allows you to use the old remotes with the newer decks. According to page 25 of this pdf it's what you need for your M309 to work with the older 6 pin remotes: