I'm back, longer day than I expected (didn't have to work after all, but helped my good friends and neighbors pack up the moving truck for 11 hours)

I gotta admit that with a dry spring ground or surface water doesn't seem likely But, a leak from one of the (or the only) return fitting, behind the liner doesn't make any sense at all - the water would be pushed through the vermiculite before the liner has had a chance to begin to wrinkle.

It's gotta be water in the ground, pushing the liner around! A couple good downpours with ~impermeable soil would result in such an issue.

Your liner shouldn't be so faded after a short 10 years - unless it was "NUKED" with chlorine or left as an acid bath for a prolonged period

As long as the liner is still whole and viable, you can use your wall brush to push the wrinkles towards the walls as the water underneath subsides. If you still have wrinkles, the only way I know of to remove them is to take down the water to ~ 2" in the affected area and manually work them out (there are a couple different ways to achieve this). You're basically resetting the liner. However, with a 10 year old liner in the faded condition you describe, I'm not sure you won't do more harm than good

If you can live with the wrinkles, do so for now and save up for a new liner. Not the most encouraging advice, but that's the best I can do.

Please feel free to ask of me any questions you have on this subject.