i done this a few times, The best way i found is 2 start at 1 end, check which end by where they meet in middle, cause they slot 2gether 1 behind the other, And then get the slots in as far as you can, Then get a thick tee shirt and an lump hammer an bang them in,, works every time, If you a bit unsure use the palm of your hand 1st and see how you get on,,