The problem here is that I don't think you actually know any of the private key. Let's take a simple pattern for the sake of illustration.


If you move the first digit to the end, you get:


If you instead move the second digit to the end, you get:


Even the tiniest change in what you cut and pasted will result in a vastly different private key, so I don't think you can say with any certainty that you know any of the private key.

If you have tried every cut and paste of 1, 2, 3, 4, and 5, consecutive digits, then you might as well try 6+ consecutive digits, since the number of possibilities gets progressively smaller and it is trivial to try. The next thing might be to consider if instead of cut and pasting, you actually swapped two different sets of numbers.

Also, be sure you are checking both the compressed and uncompressed address, as bitaddress.org generates both.