I too own the 909, and had the same frustration. I went a much cheaper (and lazier) way: the side hole made for bare wire fits one of the prongs of my spade cables. The other prong stradles the side mount, away from the other output post for the respective channel. In fact, the geometry of the back of the amp also serves to hold it snug in place. I covered the other ("free") prong with some insulating caps, and it seems to work OK. Not ideal, I know, but a whole lot easier than changing the binding posts. You will leave a mark on the spade prong that goes in from the fastener, but if that's OK for you it may at least be a temporary solution.
Of course, if I set my house on fire doing this I will give you an update...
Of course, if I set my house on fire doing this I will give you an update...