Editing IBM 5120 Maintenance Guide (section)

== Inspecting the Chassis ==

Inspection items in order:

# '''Main PSU bulk filter capacitors''' — visual inspection. These are the highest-likelihood failure point.
# '''Series-pass regulator transistors''' — heatsink-mounted; check thermal paste.
# '''9-inch CRT and deflection board''' — inspect for cracked solder joints around the flyback transformer.
# '''Phosphor''' — check for burn-in (static images from years of unattended operation).
# '''8-inch floppy drive belts''' — perished urethane is the dominant failure on these drives.
# '''Spindle motor brushes''' — wear is common after 40+ years.
# '''Head load solenoids''' — fatigue.
# '''Drive cage carry handles''' — plastic fatigue reported.
# '''ROS modules''' — reseat in sockets (oxidised pins).
# '''PALM board edge connector''' — reseat (most common cause of "dead PALM" symptoms).