Your approach to the track assembly is ok. Now, just use a tape measure on the gaps and then look at the chart to find what tracks will fill the gap.
Some items that will throw you are the switch through lengths. O48, O60 and O72 are different lengths that are fractions.
Putting the switch track end to end on the through without the 1 3/8 half-road bed (for O60 & O72)) pieces is ok. It comes out shorter in total length. Same for the diverging or turn-out.
Snaking the switches to get from outermost to the innermost loop is ok. The fitter pieces really help with center rail to center rail spacing or moving the loops in relation to one another.
One issue that will get you is that the O60 turnout will not replace an O60 curve. I don't know why it was designed that way. It makes the O60 kind of an orphan.
My concern is that the center metal piece of the problem switch may be dead. The roller is fine on any of the rails getting power. The wheels get common. It sounds like you are describing when the roller is on the center piece it is dead.
Check the position of the roller when the caboose lights go out.
You'll have to remove the offending switch to diagnose and repair it.
So, check the exact position of the roller.
