Replying to Switch Ups

It is summertime and now with no possible access to any skiing facilities I have taken things into my own hands building my own Msnow jib setup. Whenever I try to do a switch up (new trick to me) I try to scissor grind, pretzel grind, whatever, holding the grind on PVC is especially hard, maybe I should build a different type of rail than the one I have? It doesn't seem to be a problem for other people on my setup though. I need suggestions on maybe better ways to go about trying switchups, or practicing them somehow for that matter. Whenever I try to do the grind I slide off to the side almost instantly, and when I pop and turn my skis won't stay in line and I land all awkward usually making my skis bump into eachother. Any suggestions on this trick?