Anybody know how to change the ABS ALB brake modulator unit?

[robodog]

Have a 91 NSX, the ABS ALB pump keeps cycling every few minutes. I changed the fluid, but it still happens. When I stomp on the brakes it goes away until I stop and restart the car. After restarting the car, the pump then continues to cycle every few minutes.

I'm thinking I probably need to change the ABS brake modulator unit but the service manual does not seem to provide the instructions for doing this. Any ideas?

Thanks

Robodog