What is an indicator of a failing starter motor?

Intermittent engine starting is indeed an indicator of a failing starter motor. This condition often manifests as a situation where the engine sometimes starts normally and at other times fails to engage, which can be due to worn or damaged components within the starter motor itself. Common issues might include faulty solenoids, worn brushes, or internal circuit problems that lead to inconsistent operation.

The other options do not align with typical symptoms associated with starter motor failure. Increased fuel economy is generally a sign of a well-functioning engine and optimal fuel management rather than an indicator of starter issues. White smoke from the exhaust suggests potential problems related to fuel or oil burning, not the starter. High engine compression is a sign of a healthy engine, indicating that the pistons and rings are in good condition, rather than a problem with the starter motor.