What indicates that a plug may exist in the axle when observing brake issues?

When gear lube is found inside the brake drums, it strongly indicates that there may be a plug or seal failure in the axle. This occurs because the axle assembly typically contains lubricants that are used for the gear mechanisms. A failure in the axle seals can cause this lubricant to leak into the brake drum area. The presence of gear lube on braking components can lead to compromised braking performance, as the lubricant can contaminate the brake shoes or pads, reducing friction and causing poor braking action.

The other options point to various brake issues, but they do not specifically indicate a problem stemming from the axle. For example, a grinding noise while braking could suggest worn brake components or insufficient lubrication in the brake system, while pulsations in the brake pedal often indicate warped brake rotors. Fluid leakage from brake lines is separate from axle-related issues and suggests a problem within the hydraulic braking system itself. Therefore, finding gear lube inside brake drums is the most telling sign of a potential axle plug issue.