If you can poke a few holes with a very sharp object like an Awl, Small center punch etc. you can then use thos to pry the seal out. Do be carful not to score the shaft or housing.
I do believe years ago I heard of being able to momentarily pinch or block the return hose to "blow" the lower seal out, not sure that would work though.
Might just drop the box so you have open access. Someone else may chime in as well