lock up

when i try to do a U move i lock up 80% of the time. i tried many different fingertricks for the move but couldnt make it work. it locks up by having one edge hit the hole in the middle. i have a gan pyraminx standard and i couldnt find a way to tention it, any help?

I own a c4u DIY speedcube as my main but it seems to lock up too much. I cant seem to get good times on it. Anyone have ideas on how to mod it?