What testimony does the court need to provide to establish that a boxcar door has a broken handle?

What the testimony reduces to is that the broken handle did not appear abnormal; it was rusty but this is a common condition for railroad equipment. There was no testimony on the critical point; was there rust or deterioration on the surface where the break occurred? The record is silent on this point. From reviewing the record, there appears no evidence that a "break," in the strict sense, even occurred, only that the handle "fell off." It was sheer speculation on the jury's part to infer that rust on the outside of the handle had anything to do with the break on the inside of the boxcar door. Such a conjecture cannot substitute for proof of an essential fact. (Reese v. Smith (1937) 9 Cal.2d 324, 328, 70 P.2d 933.)