I would be surprised if boats were built without a pivot, class rules require one. But it is possible
To be thorough I think the best way is to measure a few things against the class rules;
Section 26 contains mast details and a little further down the sail dimensions in Section G.
Some common problems that may not be helping are;
Sail head not being hauled to the top of the mast – if you cannot see to check this then turn the boat on it’s side
The leech is badly stretched causing the boom to sag.
The rig is not setup correctly – e.g. too much rake.
It is well worth taking some time to get the rig setup correctly, this article explains how;
New masts have fixed goosenecks and assuming the main sail head is hauled to the top of the mast there is usually a little bit of tension on the luff. So you should not need to pull the boom below the black band. A shackle or untidy splice maybe stopping the sail going to the top. Or there maybe too much stretch in the halyard. A lot of people use a plastic bobble which does away with the need for splices and shackles.
Hope that helps