Well it sounds like you have a brick going into Fixed 1 on the TIU and then out to a terminal section of FT, which should be fine; although with 3 ovals and ?? feet of track, I'm not sure how much power is making it's way to the outermost points of the layout. In addition, that brick has a very fast acting short control, so it's unlikely that's where your issue is. It's not clear to me whether the AIU's are hooked up or not, but I would leave them out of the equation for now and just control the FT switches using the manual switch controller and track power until you get them straightened out and find out why the switch LED's are blowing.
Get that dvm and check your voltages on both sides of the TIU; at the terminal section; and around the track and at the switches. That's a good way to find out if excess voltage is burning out the LED's. Also, run your hand all around the FT track surface of all 3 ovals and make sure there are no hot spots.
