Which of the following should NOT be checked for safety on a TLB?

The correct answer is based on the priorities of safety inspections for a Tractor Loader Backhoe (TLB). Checking the fuel gauge would typically be less critical in terms of immediate operator safety compared to other options. While ensuring that a machine has enough fuel for operation is important for performance and efficiency, the other components listed are directly related to the safe operation of the equipment.

The horn and mirrors are crucial for ensuring visibility and communication with others on site, which directly impacts safe usage. The loader arm service lock is vital to prevent accidental movement of the loader arms while maintenance is being conducted. Similarly, the seat belt is a fundamental safety feature that helps protect the operator in case of a rollover or sudden stop, making it a top priority for inspection.

In summary, while checking the fuel gauge is part of general maintenance, it does not directly relate to immediate safety concerns, which is why it is considered less critical in the context of a safety check compared to the other items listed.