This weeks AWST had an article about how Lockheed plans to lighten the STOVL JSF variant. Changes include:

Reducing the intervals between the interior structure in the wing so a thinner skin can be used.

Reducing the length by 14 inches and decreasing the size of the weapons bay (This means it cannot carry the JSOW or 2000 lbs bombs)

Rounding the loftline of the fuselage behind the cockpit to improve drag and add more fuel

Redesigning the electrical system and decreasing the battery size

They also made some virtual weight losses by changing the auxillary inlet on the top of the plane for better pressure recovery (Whatever that means)

These changes should get the fighter back on track and help with speeding up the production process.