gnashings,
I've dealt with AE1's over a number of years & never seen one that required being cocked to change lenses/speeds etc. And having dealt with camera operators of every skill level I think I can safely say there's a lot of fumbling around out there.
The blank frames you're experiencing is a failure of the closing curtain latch which is an electronicly controled timing mechanism. Could be dirty, have a film on oil on the magnets surface, bad solder connection. Or, it could be the circuit itself.
If you decide to have someone service the camera, send some negs with it so the tech can see whats going on. It's a not uncommon problem with that camera.