I knew right away, so maybe it's regional. I was told the machines are programmed with a certain value above which they'll pay out, (e.g. once the machine has

I knew right away, so maybe it's regional. I was told the machines are programmed with a certain value above which they'll pay out, (e.g. once the machine has taken £200, allow a win, then repeat). If the machine is not ready to pay out then the claw just releases on the way back up to make it look like you came close to winning. Likewise block-stacking machines - it's a little harder to tell with those though as you need to get all the way to the top before you'll know. The block very clearly jumps to the next space on the top row if you time it correctly and it's not ready to pay out.