I don't know how your second-post proposal would work if you can't even get the arm/cart to balance out with the counterweight at its lightest setting. The tracking force adjuster adds downforce to the business end; removing the spring isn't going to help you get the cart back down from up in the air. Sounds like you might need to add a headshell weight, but why not first check the specs on your new and old cart's to see what the weight difference might be? If you don't spot a culprit there, maybe email Cardas to ask about any potential difference in wire weight with their product. Or it could be both factors combined. Regardless, adding some mass to the headshell is the usual method to solve this problem.