I just assembled mine with the same size tubes. I assume you are having a hard time getting the z nut traps into the pipe. I had the same problem. Two pointers here. Make sure you drill your holes for the screws big enough into the z pipe. They need to go through easy before you put the inserts in. I drilled mine close to 5mm per the instructions. Then if you line it up carefully you can “convince” or “persuade” the inserts into the pipe. I did it a little more brute force like, but you could just sand down the edges until it goes in easily. Should not be any reason to reprint these.