[Mk.32]

How thick is the metal you are using? 1/16th inch is often plenty and half the weight of 1/8. Also solid plates are usually over kill, we saved like nearly 2 lbs by pocketing out a a 17inch circle of alum.

You could swap to 6inch wheels [loose some bump abilities...] and save some weight off those pneumatic tires.

And as said above check to see if your scales are correct, weigh a person who knows there weight[safety first though] to see if it is off.

This late in the game rebuilding large portions of your robot is probably to late... best try finding parts you can swap or take off. Large pieces of metal are a good place to start. Figure out what needs strength and what doesn't. And don't be afraid to loose some functionality. Lesser under weight robot is always better than a over weight robot of any caliber.