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Flipping the foam is no big deal, unless the cover is four years old or more. That seems to be the magical cut-off date at which the vinyl has shrunk and/or lost enough flexibility to make it a real tough job.Don't try it alone - 8-)
Chas, is it normal for water to collect on a new HS cover? Would you tell a customer to deal with it or would you change it out for them? Here's a photo of my 2 year old cover:
The larger the spa the more apt the foam will bow in the middle like that even if it's 2# density. Changing the foam core is a major pain IMO. If it is just an aesthetic issue for you I would do my best to ignore it. It should not get worse, once it bows like that it pretty much stays as is.
"The cover looks smallish" If you are talking about mine, no it's a perfect snug fit.....I love it!(and it's puddle free)