It's been a while, but I think you are on the right track. IIRC the problem with a standard screwdriver is it's tapered so sticking it in the slot doesn't engage the little clip enough to get it to let go. I have a small long flat blade screwdriver that's bent on the end. Just can't remember which way it gets it to let go.one way will make it really grab and the other let go..toward the block or away. Like I said it's been a lot of years since I messed with that, sorry.