Spinal implants and methods of extending pre-existing spinal implant constructs. The managing platform uses the transaction data contained in the transaction message and other information to determine whether the transaction satisfies one or more payment rules previously established by the cardholder. In another embodiment, the assembly further includes a control system that controls the backwash system and the agitation system. The configuration is such that the shortest track travel time using the fine actuator is larger than the inverse number of the local maximum of a flying-height fluctuation frequency of the suspension by the fine actuator.