You don't even need a photo for Pullman to say you need to buy a big step. That's their default setting, unless you own a big step in which case it's time to but a chisel.
If you really want to check you can try a NSEW tamp. This means that you intentionally touch the tamper to the edge of the basket in the four points of the compass positions. If you can't see a difference in this probably not much point. If you want a cheaper 58.4mm tamper the Barista Hustle one is pretty good.