bbinnard,
Exactly, s3d doesn't execute or allow preloading the y combiner for the first tool change.
I could only go as far as unloading old tool, but cannot preload new tool. This is what I use in tool change script :
*y combiner length is 120mm
T[old_tool]
G1 E-120 F4500
T[new_tool]
G92 E-120