Correct application of flow-control accessories can greatly reduce the time and money spent on diagnosing well problems (such as tubing or leaks) should they occur. Strategically placed profile seating nipples above and below the packer aid in isolating the leak to the packer or the tubing string. Once the source of the failure is known, a plan can be formulated to resolve the problem. Not much can be done to fix a packer leak without well intervention. However, special flow-control devices are available to straddle across sections of leaking tubing and deter work overs. In either case, the knowledge gained by being able to use flow-control accessories and devices to perform downhole diagnostics is extremely valuable in planning corrective action to be addressed in the subsequent work over.