I'm sorry I can't be more helpful but I have always had to drill holes in the Peco sleepers. Of course with a mini drill this only takes a couple of seconds each hole. Don't struggle with the pins as you are doing now because that way lies accidents and damage, either to the track or yourself. I have just tried a couple of pins doing as Peco advise and sure enough they do go through the sleeper but it requires a VERY firm grip on the pin and a not inconsiderable pressure. I can't see that youngsters would be able to cope at all.