I am having trouble trying to figure out the right curves to use on a siding for my xmas tree layout. Can't seem to get the siding to be truly parallel to my main line. Using Lionel Fastrack, the switch is an O36; I've tried a mixture of O36 curves, quarter, half curves, and tried mixing in an 048 half curve. What is the best way to fix this? Do I need to insert a different radius quarter/half curve in here?