I've begin to get an usual knock coming from the engine when on plane. Not continuesly, not all time, only notice when on plane. Doesn't seem to have lost any power/performance. Checked lower unit drain plug (magnetic end) and had only fine shavings. Not gear pieces. When I pull in and out on the prop, I do seem to have a very small in/out movement. (1/16 inch or maybe a pencil lead thickness)? But, the knock created when pulling in / out does sound very much like what I hear when running. However, the knocks seem to have 2-3 second time interval between them? That seems odd if related go a prop spinning at 3,000 RPM or more.
The motor is a 98 Johnson Fitch 150. Probably has less tha 300 hrs on it. Came with a Ranger 461 VS. Thanks in advance for any ideas/prior experiences with this.