Ok, I am sure the answer is right in front of me but I am not seeing it. I am working on the rear set of cylinders/valve gear on a Regner TSSD 0-4-4-0 Mallet. She has full walschearts with lap/lead. I can get the forward direction set dead on with equil travel of each slide valve in relation to the ports. But shift the valve gear to reverse and it all goes to ****. Instead of being also dead on, it will pull the slide to far one way and barely uncover the other port at all. If I reset the motion to reverse being spot on, it throws off forward. What am I missing?