We don't have any specific instructions for that filter. The manufacturer has discontinued it.
If you scroll to page 3 on the following document, there is a Cartridge Replacement section with generic instructions for replacing a filter in a housing:
http://www.waterfilters.net/PDF/Filt...structions.pdf
If you purchaesd a new oring, you'll want to replace the o-ring you have instead of following the o-ring instructions in that document.
To screw off the housing, sometimes you need to use a wrench if it is stuck. I'm not sure if you'll need one or not but if you do, the strap wrench works well for this housing:
AquaPure 68900-34 Adjustable Strap Wrench for Water Filter Housing Canisters and Sumps
You don't want to use a wrench for tightening the housing because it can damage the oring. You only want to use the wrench for removing the housing sump.
Thank you,
WaterFilters.NET