I'd take the brakes apart and look at them before modifying anything. A leaking axle seal or a sticky wheel cylinder can cause what you're getting. If you end up replacing the cylinders make sure they're the same, if you can't get them both from the same brand, pull the rubbers back and measure the diameter of the pistons. I replaced the rear cylinders on a truck years ago and the parts dept ended up getting them from 2 different sources. While that shouldn't have been a problem, one turned out to be the wrong part- it looked identical, bolted right up, but one was slightly bigger than the other and I chased the brake pull for days. Since the truck came in with no brakes I didn't instantly suspect the cylinders.