IBM ThinkPad X30, ThinkPad X31 (MT 2672 Manual page 118

Removing and replacing a FRU
PC Card guide ( a ) and audio connector retainer ( b )
are attached to the system board. When you replace the
system board, reinstall those parts to the new system
board FRU.
a
When installing: Attach the system board so that the two
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ThinkPad X30, X31 (MT 2672/2673)
b
small projections on the base cover fit
into the holes provided, and then tighten
the screws.
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