Okay, 123 model. i understand that the blue vacuum line going into the firewall on the driver's side is responsible for the rear seat-back locks. Is this line supposed to be running through a door lock check valve? It appears that it is plugged into one side of a two output door lock check valve. The other output is plugged up with a rubber cap. Seats don't lock. Vacuum doesn't hold on trunk lock when sitting overnight. Also, if I use a hand pump to test the vacuum on the actual door lock check valve supply side, it holds between 10 and 12 psi until I lock and unlock the driver's side door...then the vacuum reduces to maybe 5 psi. Any suggestions?

Thanks