Hyde, I can commiserate. Black is a tough color to get right, and even if you've had good results in the past, every so often a certain project will cause problems.
FWIW, I agree with your decision not to attempt to strip off what's already been applied. I think there's a good risk it'll ruin your project. I also agree with Mike's advice to try olive oil or another condition to see if it'll even out the color and finish for you. If all else fails, try to redye, but honestly -- I think I'd just try to touch up the problem spots and buff -- not redye the entire seat. That should be the last resort.
I'm keeping my fingers crossed that you're able to salvage this! Let us know how it works out.