Editing IBM PC XT Maintenance Guide (section)

== Connector & Socket Care ==

Oxidation on socketed ICs is a common cause of seemingly random faults.

=== Reseat these ===
* '''U18 and U19''' (both BIOS ROM sockets — the 1986 BIOSes use both as part of the BIOS).
* '''Intel 8088 CPU socket.'''
* '''Optional Intel 8087 FPU socket''' (if fitted).
* All four banks of RAM.
* ISA edge connectors — clean with isopropyl alcohol on a foam swab; if blackened, use a pink eraser on the gold fingers.
* DIN-5 keyboard socket on the rear panel.
* MFM data and control ribbons at the [[IBM Fixed Disk Adapter|Fixed Disk Adapter]] and at the drive end.

Apply DeoxIT D5 or equivalent contact cleaner to socket pins and edge connectors.