What are the signs that a treadmill needs lubed?

Signs that a treadmill needs lubrication include a noticeable squeaking or grinding noise during operation, a rough or jerky movement of the running belt, and increased friction when walking or running. Additionally, if the belt feels sticky or is not moving smoothly, it's a strong indication that lubrication is required. Regular maintenance, including checking for these signs, can help prolong the life of the treadmill.