There are very few seals which I find don't go in quite easily by hand.
as you know you have to stretch the seal to get it where it needs to go, but once you do that its then too big to go into place .how ??
id agree with that too, but there have been times with the smaller seals that happen to be a right bit down a throat of a gland that can be a pita so the tool the op was looking for would be a godsend at times in them cases.There are very few seals which I find don't go in quite easily by hand.