Struts are wearable parts and go bad with time. They are just weak and could not handle the extra weight of the ladder. I believe new set will solve your issue.
I have MY13 and recently I have to push the liftgate up to get full lift eventhough I do not have any extra weight.
My MY13 is on its 4th battery now. The previous one last 15 months only. Thankfully the dealer replaced it under extended warranty. I believe the hot weather here in Middle East kills the battery sooner than expected.