Apple ColorLaserWriter 12/600PS - Manual (Page 235)

IMPORTANT Insert transparencies so the white strip goes into the printer first.
Some transparencies have short strips that don’t extend fully across the page.
Align these transparencies with the short strip on the left-hand side of the
stack. Inserting transparencies incorrectly causes them to jam.
Slide the width guides
so they rest against the
transparencies. If the
transparencies bow out
even slightly, the
guides are too tight.
Load transparencies so the white strip
goes into the printer first.
Use only transparencies recommended
for use in the Color LaserWriter 12/600 PS.
If a transparency has a partial strip, align
the strip on the left as it goes into the printer.
If a transparency has a full-width paper strip,
make sure the paper side is up as it goes
into the printer.
211 Loading Paper