I am trying to replace all the o-rings and the shaft seal for my Pentair Challenger pump. I have gotten all the way to the seal plate where there are 4 bolts. I have gotten 2 bolts off and the last 2 will NOT budge. Any ideas on how to get them out? I have tried w-d 40 and just about everything else you can imagine. I’m at a loss and I got so far and am so disappointed I am not able to get those off.