Harmonic Balancer Big Block Question

[72orangepumpkin]

I'm trying to pull this part off a big block 72 motor and have never done anything like this before. When looking at the front there are 4 bolts... one down the center which apparently bolts to the shaft and three smaller bolts in a triangle. When I pulled the three smaller bolts out the front pulley came off. I then pulled the center bolt out and expected the rest to slide off the shaft, but the balancer and pullies are still steadfast. I'm trying to get it off without damaging the the pullies or the timing cover behind it!

Any ideas? Does this look familar to anyone? The orange ring behind the pullies is the harmonic balancer right?? Thanks, Chris