I usually see two small adjusting screws at the bottom sections of most cameras, even on the electronic Minoltas, but with the original Canon AE-1 I see none when I remove the bottom cover.
The camera works fine, (despite some past apparent water damage). But the fastest speeds (250, 500, 1000) emit no light onto the film. I need to slightly increase the first curtain's tension so that there will be a slit at those fast speeds. Thank you. - David Lyga
Look at the electromagnet next to the contacts for the winder. Within its mounting plate you see two holes perpendicular to the front/back of the body. Through these holes you should see the gears.
The gear next to the front is setting the 2nd curtain, the one to back the 1st curtain.
Each gear has 4 tiny holes, use an appropriate 2-prong tool for twisting the gear.