How far the once mighty have fallen. This sounds less than encouraging for Williams
"There is one fundamental which I don't want to discuss publicly," said Russell, who will start 19th for the F1 season opener.
"We understand what that is, but it doesn't mean we can wake up on Monday morning and rectify it.
"To change something so fundamental will take months of development, work in the simulator and designers working out how to do it, and that is what needs to be done at the moment.
"Unfortunately we are looking at a number of races before we are going to be able to fight, and that is just where we are at the moment."
Asked how big a leap forward that change could deliver, Russell said: "I think once we have solved that fundamental there will be a big leap.
"We will probably still be at the back of the grid, but with the chance to fight rather than like it is at the moment. The fact is we don't have any hope because we are too far behind."