Epson 4000 - Manual (Page 59)

4. Position the SIMM at an angle over the empty SIMM socket,
as shown below.
5. Push the SIMM into the socket until it is seated firmly in the
slot. Then tilt it upright, as shown below, guiding the hole
at each end of the SIMM over the retaining post at each end
of the SIMM socket. If it does not go in smoothly, do not
force it; pull it all the way out and try again.
6. Replace any option cards you removed. (See page 4-14 for
instructions.)
4-12 Installing and Removing Options