Well if you remove the tab that enables/disables the detent, and shave a little bit off the top of the black bits next to the red bit, that should make it easier.
If you're not sure which black part I mean, remove the top cover and move the throttles into the detent. You'll see that the throttles have to get lifted above the black part of the tab.
And just make sure you're shaving a little off at a time and keep testing it until you're happy, you don't want to go too far!