I need to change the headband pad on my HE90 but I've never actually done it before. Can anyone here talk me through it so it makes sense and I don't break something? I think the cups have to come off but I'm not positive. Any help would be appreciated, Gary.

I don't exactly remember, but I think it becomes obvious once you pull one of the ends of the old pad towards the middle.  I think there are some small screws underneath that you have to remove and then you can pull the whole spring steel part out.

I think you have to unscrew one earcup to gain access to the headband to do it.  I can't remember exactly either.  Luckily the headband last a lot longer than the earpads.

Thanks guys, I'll use the info and investigate further.

Should be 2 small screws  behind where it says HE90 on the headband swivel

Be careful with those screws as... well Sennheiser uses the cheapest crap they can find so they strip easily. 

Well, I finally got it and what a pain in the ass it was. Stretching the pad over the headband was the tricky part and pretty time consuming at that. Spritzer, I think I may have stripped one of the screws ever so slightly but it still had some bite so I think I'm good. I appreciate all the advice guys, thank you. Gary