You measured 1.375 and the hose is 1.400= delta .025 or .0125 per side to squeeze, sounds perfect to me. Use two clamps if you want to. Your 40th of an inch is correct but who measures in 40th's? smile
If you fix the pressure problem you will fix the leaks.

Right is right, even if everyone is against it, and wrong is wrong, even if everyone is for it. - William Penn