Mikemartin forgive me for not knowing much about this pan. Could you measure the distance from bottom of pan to the top of inside of the draw off port. Your draw off port is a funny thing when you want liquid to flow out of it. Having 100% boiling water wont flow that well out the port now try it with 66% sugar and it is a totally different situation. Your dancing with the devil if you get below the top of the port opening because you will be only drawing off (for the lack of a better term FOAM)

If your port was 2" no problem 1/2" big problem.