I agree regarding the cover, it is a pain but I managed it eventually, I think it's the fact that because you have not done it before and this applies to most of us, you tend to be very cautious in your approach incase you break something, but sometimes you have to be a bit brutal when pulling something apart, the most important thing I've found is absolutely make sure that you have found every nut, bolt and screw that is holding something in place, and then check again.
Unlike Timmus and A2Steve who does this on a regular basis it's all a learning curve to us mere mortals.
You WILL manage it if indeed it needs to be changed.
If I can do it, anyone can if you think and take your time.
Oh just to add, a head type torch is a great thing to have, it's pretty dark up there. ?