hi I have recently replaced the bottom entry ball valve in my close coupled cystern. the problem i have is that the new ball valve has a slightly longer arm than my original which is 12 years old. the float is fouling the side of the tank as it rises and doesnt fully shut off the flow allowing it to overflow after a while. i have tried adjusting the arm with no affect. can i replace this valve with one of the torbeck valves which don't seem to have the arm or ball float ?