With regards to the ET 183 seals, I don't know how others do it, but I check them one at a time to make sure they have the right amount of sealing crush on them. Too little could cause them to leak and be ineffective, too much will cause them to crush and squish out around the sides. I just put one in and check it by holding the timing cover home with hand pressure, then remove the cover and see the witness mark impression left in the rubber. I don't bother with timing cover gaskets at all, so this is easier to check. I think lots of cases of poor oiling to the spindles are as a result of these seals not being set up correctly.