2007 M-8 reverse dead?

Just wondered if there is a way to diagnose whether a mechanical reverse failure is due to a acuator or ECU? When the reverse button is pushed the headlight flashes and the wrench illuminates on the dash, but the sled stays in forward and the reverse beeper doesn't come on when the engine is throttled up.

I figured I would replace the acuator if I was sure that was the problem, but if not I would just add the aftermarket lever and call it good.