Got the board as a present from one of our friends a while ago, and could finally solve it consistently. (Note: in the European version you don't start in the middle, as it's impossible to solve the board if you do it that way)
My grandad has ha done of the since I was a kid. 30 years at least and we have never been able to do it. Frustrated I looked online just now and saw the 37 and 33 differnece. We ha e been removing the centre marble on the 37 for 30 years.