First, did you use the pin/uni that was provided with the board, or something else?
Secondly, it sounds like your release pedal may be stuck half way between the "press
pedal to relaese position" and the pedal back and locked down almost flush with the deck position. When the pedal is pushed back to the locked position, the mast car should be able to lock in
any of the slots in the rail.
Can you check to see if the pedal can be pulled forward toward the front of the mast track, and if it re engages in that position?
Hope this helps,
P.S. the pin that was supposed to come with the board is about the only one that will fit securely
under the locking U clip.
When we first had this issue (on the first Phantom ever imported into the US) we had to borrow a pin/uni from the Exocet folks as their mast tracks and the ones in the Phantom all come out of Cobra.
We tried North pins/ Mistral pins/F2 pins from oler boards, and none of them fit securely.