you have to take the complete front off the dryer and the front seal unit and you can just about struggle a bit to get at it by wedging the drum up to create maximum room. you can still only get one hand it which makes getting the nut off and back real fun
as a quick tip
to hold the cap in place when you only have one hand use string looped over the top of the cap which holds it in place while you put the nut and washer on