Maintenance is "the servicing of the machine in order to make it work in accordance with its original specifications and any changes to those specifications authorized for that machine. . . ."
[T]he term 'maintenance' has a much broader temporal connotation [than 'repair']. The Senate Report on section 117 characterized 'maintenance' as including 'checking the proper functioning of [ ] components.' . . . Thus, maintenance, or 'servicing,' was meant to encompass monitoringsystems for problems, not simply fixing a single, isolated malfunction."