HUT was kept at Kennedy Space Center (KSC), but its spectrograph was returned to Johns Hopkins University in October, 1988. Although protected from air and moisture in an evacuated housing, HUT's extremely sensitive UV detector had degraded with time. An improved spectrograph incorporating a new detector was installed in January, 1989.
After an extended time in storage, WUPPE's precise instruments required recalibration. Rather than ship the large, sensitive telescope back to the University of Wisconsin, a portable vertical calibration facility was built and delivered to KSC. Calibration was completed in May 1989. WUPPE's power supplies for the spectrometer and for its detector were returned to the University of Wisconsin, where they were modified to reduce output noise.
UIT also remained at KSC, where the High-Voltage Power Supply for the image intensifier was replaced in August, 1989, following a failure during testing.
During the payload recertification process in the summer of 1987, questions arose about the quality certifications of the bolts used in the Astro-1 hardware. As a result, support structures and instrument and electronics attachments were inspected for possibly faulty bolts. Kennedy Space Center (KSC) personnel removed and inspected a number of bolts for testing, and beginning in June, 1988, 298 bolts in the Astro-1 hardware were replaced.
During pre-integration inspection of the Instrument Pointing System (IPS) at KSC during the summer of 1989, a number of irregularities were identified regarding splices in the original wiring as received from the Eurpean manufacturer Dornier. These irregularities included spurs (sharp wire edges) that had penetrated the protective sleeving; improper sleeving materials applications; grouping of splices in wire bundles; splices placed too close to wire harness connectors; and individual wire strands that had been cut or nicked during pre-splice removal of the original wire insulation. Of 469 splices identified, 301 were replaced and retested, 84 were examined with no rework necessary, and 84 were inaccessible with the IPS and could not be examined without a significant launch slip to permit disassembly of the IPS. The same IPS unit to be used on Astro-1 had already flown as part of the Spacelab-2 mission in 1985. Engineering evaluation determined that such disassembly would probably introduce more problems than it would correct and it was decided that the IPS could be safely flown with minimal chance of impacting mission success.
-Text taken from a NASA press release.