How do you unlock an aerolite suitcase with forgotten combination lo?

I used my sense of touch and once I had gotten the subtle differences as I changed numbers I could start to detect when I had a correct number. It did take 20 mins or so to acquire this so don't give up too quickly. The slider that you use to unlock the case really does feel different, much loser. So when you detect this slight easing change the number to test, if it tightens up again you had the correct number when it was slack. Within 25 mins I was in the case.