I replaced the strap on my 1800ES without removing the door, however I believe if you want to replace the sort of spring-clip thingy that actually keeps the door open by pressing against the check strap, you have to remove the door as IIRC it's sandwiched somehow between the door hinge and the door. I could be wrong as that was over 30 years ago. Note the new check strap I installed will not keep the door open unfortunately, so I guess it depends what parts you replace and the quality of the replacement parts. I think the one I installed was aftermarket and it didn't come with the replacement spring thingy.
