I have been using the IR sensor mod for a while now and been great, however, decided to use the https://www.printables.com/model/240103-mmu2s-extruder-mod-r6 mod for increasing loading and unload reliability and the tower no longer worked, seemed the original design was a tad too tight.
I added a slot to the trough coupling for the new IR sensor placement.
I made it so the tower could be shifted 2mm left of the extruder (from the front).
The idler and sensor tower support is from the original designer.
How to use the sensor tower support is illustrated in one of the photos for this page.
The author remixed this model.