SteveZ Z-28

Took off the water pump and found that the water pump seal was not the culprit. Turns out it was the optispark seal in the timing cover. (Keep in mind this is a non-vented optispark on a 1994.) Now, the question is, what did I do wrong? When I put the new seal in I used a block of wood and then hit on it lightly with a hammer to evenly seat all sides. It looked to me like it was seated evenly on the cover before I reinstalled it. When I took the seal out it looked like it had been riding to one side more. I put in a new optispark driveshaft when I put everything back together. The optispark was installed correctly as well. I did put some grease on the seal before I put the optispark driveshaft into the timing cover. Could that have been the problem? And now that I have the seal out and want to put a new one in, how would I go about that without taking the timing cover off? Since I'd be working at it vertically I'm not really sure what the best way to install the new seal would be so that it would seat evenly on all sides. Should I just try and use a socket?

Thanks for the help.