At our wits end

At our wits end.  We have been using a litter robot 3 for over 3 years.  Cats have been happy we have been happy.  WE recently purchased a litter 4 to use downstairs where the 3 is currently at and would like to move the 3 upstairs.  Here is a breakdown of what we have tried to get them to use the 4.

Machine turned off sitting next to the 3  for 3 months

placing their droppings in the 4 

tried FILAWAY to ease them

tried treats

removed the old 3 completely 

turned off 3 to let their spoils take over.

Dr. Elsey's Ultra Litter Attractant

Coaxing

Trying limiting the access by making it harder to get to with obstacles

They have a perfectly clean littler 4 sitting right next to their 3 and if the 3 is not pristine they would prefer the floor to the 4

Any action i take gets an equal and opposite reaction of pissing and crapping on the floor  this has been going on for over 3 months at this point.  My fear  is the 3 is finally going to give out and the crap hits the proverbial fan.  Does anyone have any idea?