Epson 1500 - Manual (Page 157)

Reinstalling the controller board
1. Hold the controller board level and fit its right edge into the
right groove inside the board slot. Then gently fit its left
edge into the left groove.
2. Slide the controller board into the printer until it locks in
place. If the controller board does not fit smoothly into the
printer, do not force it. Remove it and make sure the edges
fit properly into the grooves in the board slot.
Options 5-43