Can't go over 2500 rpm's?

[nymack66]

Disconnect both tan wires and ground one at a time to the lock with the key switch on, your buzzer should sound. If no buzzer then its possible the tan wire is currently shorted out shorted (no buzzer working) and is holding the motor within the "low load range of 2500 rpm”?
Also can you turn the prop freely in Natural? Maybe the lower unit is broken and is locking? Reason why I mentioned the lower unit is because of the shifting issue.