A device for protecting the arm of a user consists of a protective sleeve and a tubular pouch sized to fit around a user’s upper arm. The disclosure allows for correction of non-catastrophic faults, such as significant changes of the components’ values. An exemplary method comprises determining a decoding synchronization time for each of the first and second OFDM signals and calculating a time difference between the respective decoding synchronization times. While the sample insert plate can be a consumable, the remaining portion of the apparatus can be reused. In addition, the bushing and housing assembly may be installed in a textile machine or other types of machines that use linear bushings. Upon evaluating a predefined image portion comprising a plurality of image elements, incorrect determinations are detected and eliminated.