Rocket Navigator turned in mediocre efforts in his first two starts and a gear change since his return from a break resulted in places last month at Avondale and TeAroha.
"He didn't show that much until we put the blinkers on him and he's been a different horse altogether," Lock said.
"It was a good run last time out after he missed the jump and then hit the front before he got nailed."
Rocket Navigator will jump from an outside barrier at Hastings, but Lock sees that as an advantage.
"It's better to be out there rather than stuck in behind and the wetter the better for him," he said. Rocket Navigator is one of the few runners with exposed raceday form while newcomers Lucky Edie and Shot In The Dark are trial winners. NZ Racing Desk.