Removing Isis Cranks

[Flybye]

I want to switch out the cranks on my commuter bike. The bottom bracket has an Isis linkage. I remove the central bolt on the cranks but the arms won't come off. Is there any trick I can use to get them off short of buying a crank puller?

The only help that I can give it to remember that they both unscrew to the back of the bike - no lefty loosie, rightie tightie!