The heart is slightly larger than a human head and rests at the pinnacle of the construct as you would find a gemstone set in a statue.
Drayton does have the headband but it appears to have been fused to some sort of crystal helm, which in turn is locked with a collar.
Ari, perhaps we could try to remove the collar and helm from Drayton. If the heart is set like a gemstone, then we need to strike at the place setting. Maybe the golem bane scarab will loosen the heart from the setting. It's worth a shot at least. If not that, maybe we could knock out Drayton so whatever is controlling him loosens it's grip.
To DM: Is there any purple psionic ooze anywhere that Rubius can see?