Change everything. I beleive if ll is as it should be change fluid, filter and gaskets, as I did. And if there are problems do so as well. If there is all kinds of crap floating in the fluid change everything as well. The filter can only block crap and hold it from circulating so much and so long. I have never heard a valid reason for not doing so. It is not like oil where you can not get everything out since the tranny is on the bottom it is like an oil change with taking the drain pan off instead of just the plug.