What would indicate a panto control issue when pressed to raise?

The situation where the panto fails to raise when the control is pressed clearly points to a control issue. This means that the mechanism intended to lift the pantograph is not responding as it should, indicating a failure in the actuation system. This could be due to a variety of factors, such as a malfunction in the control circuitry, an issue with the power supply, or a fault in the motor that drives the panto.

When the panto does not respond at all, it suggests that the signals intended to activate the lifting mechanism are either not being transmitted correctly or not being executed properly. This scenario can arise from a complete loss of communication within the control system or from a safety feature preventing operation due to another detected fault.

Other options like the panto remaining in the up position, raising too quickly, or making unusual noises, may indicate operational issues or mechanical faults, but they do not directly point to a fundamental control failure as clearly as failing to raise, which confirms the control issue explicitly.