BOLEX Super 8 cartridge projector Instruction Manual page 11

Set the speed selector to 18 or 24 f. p. s.
Remark
Should a film not load automatically, move the film reinsertion lever
over for 3 seconds. Do this however only when the previous film has
been rewound (red warning light off).
If this lever is accidentally moved during projection, the projector
will stop, and can be started again only when the lever is released .
9
Focus the picture.
Frame the picture.