Napa should have the seal, SKF 11055, order two of them, they bend and deform pretty easy. It's not hard to pull the sector shaft back, at most, you might have to make a new gasket. If you don't mess with the adjustment, it will go right back in. Installing the seal with the shaft in place will be much harder than without the shaft, start making a seal driver now. A small diameter pipe with the right ID to slip over the shaft and long enough to hit it squarely with a small hammer. Even with a good driver, it's easy to bend the seal.
