I can answer both of those questions.
1) Did you change anything besides the Zealot? Please post either an MPQ or a list of all your changes, as described by DoA in the "To Modders" sticky thread.
2) In the iscript for the unit (this is ICE/ICECC again,) a line is added in that says, to put it plainly, "Display the active overlay x at the coordinates 0,0 from the unit's center" where x is the number for the Maelstrom overlay...if I'm not mistaken it's nine-hundred eighty something--wow, it's sad that I know even generally what some of the overlays are...