Intermittent Errors During Backup

This document outlines the field change procedure for TA81 tape drives experiencing position lost errors or serious exception errors during backup operations. The issue is identified by status event codes 11 or 12, or a write tape mark check error. The solution requires replacing three removable EPROMs on the STI interface module (29-25345-00) for units below revision D01, effectively updating the micro-code. The procedure includes detailed steps for positioning the tape deck into maintenance mode, removing and installing the EPROMs, marking the module revision to E01, and performing a power-on self-test to verify the installation.