Starter motor won't disengage

[Super Glue]

hey guys, the starter motor wont disengage when i start the engine on my auto series one v6 vg ute. i've replaced the starter motor, ignition switch and tried changing the regulators, but still the same problem. This all started out of nowhere two weeks ago and i havent driven it anywhere since then as when i put it in gear, the starter will retract from the flex plate but you can still hear it freely spinning and if the engine if left running, a burning smell promptly follows. When i start it and dont put in gear, when i turn the ignition off, the engine will shut down but the starter will continue to crank the engine over, i then have to resort to taking the battery lead off to get it to stop. Does this narrow it down to a wiring problem or is there something else that i have missed?

please help, any advice much appreciated.