Hi Peter — first, I would recommend you locate and correct the cause of the burnout, if you’ve not already done so. Next, I would bring the controller, along with any wiring diagrams you have, to a electrical contractor who specializes in industrial and/or temperature controls. They will not need to know your product since they have the wiring diagram. Plus, they have quick access to the replacement parts.
This is not a guarantee this contractor will be interested in helping you. But you may get lucky!
Good luck!