What should be done to address an equalizing reservoir leak?

Addressing an equalizing reservoir leak involves ensuring the effective use of the train's braking system. Placing the automatic brake valve cutout valve in the passenger position allows for the system to continue functioning without the effects of a leak affecting the braking capability of the train. This setting redirects the flow of air and aids in maintaining system integrity by isolating the leak, thus allowing for safer and more controlled operations until the issue can be resolved.

The other options would not effectively manage the situation at hand. Increasing train speed would potentially exacerbate the problem, making it more difficult to control braking. Reducing the amount of cargo does not directly address the leak issue, and while reducing load can have an effect on braking performance, it is not a direct remedy for the leak itself. Replacing the reservoir may seem like a solution but is not an immediate action that can be taken in response to a leak—it's a more involved process and doesn't assist in the short term.