Chance is a tricky thing to talk about. Those who try to argue that the positions of "words" on a DNA molocule are equivalent to a series of coin tosses, miss a lot of underlying factors.
For example, if I ask what is the chance of flipping ten heads in a row, I get one probability. If I have already flipped nine heads and ask for the probibility of flipping a 10th, I get a qute different answer.
Evolution is always working on the 10th toss. The prior history does not need to be taken into consideration when projecting the odds that a mutation will be favorable or unfavorable.
When you look at the monkey typing analogy you have to consider that every time a "correct" word is typed, it is added to an existing and accumulating list of correct words. The list of correct words is never diminished or lost. That is what is known as the process of descent with modification, and that is what is known as selection.
No it is not working on the 10th toss and that is the great lie of evolution - that it just takes a little mutation to achieve great things. I have already explained how because of genetics even after such a great change is accomplished it would be very hard to spread it through a large population. In order for evolution to have been responsible for the descent of man from an amoeba thousands of new genes, thousands of new proteins, thousands of new characteristics had to have arisen. These things could only have arisen by the creation of new genes and to make a gene that works takes a large amount of random tries and each one up to the last is the first try. The reason is simple - selection does not know what it is looking for, selection cannot act on a gene that is not working yet. Selection can only act when the gene is complete and in working order. So you cannot create a gene through selection, it can created by random chance and that is an almost total impossibility.