According to the PDF...the boom vang is gas loaded...my guess is that you've lost some gas and are no longer getting full extension upwards. Moving the vang will not help. Suggest fitting a new vang...perhaps a screw type adjustable one (like Schaeffer uses) that will allow you to experiment with the angles a bit. MY in boom furler uses 89 degrees so I wouldn't trust dockside speculation unless you know the proper angle from the manufacturer. There are phone numbers on the above pdf link...why not phone or fax them if you are not getting e-mail answers?