Popping / Creaking jacks
There are a couple of threads on this. For popping the recommended fix is to add striction fluid to the hydraulic fluid--LCI has a page with instructions for this, as the problem is well known (you can download one from the website). You might also try wiping down the jacks with a clean cloth and spraying with silicon (the "dry" version that will not attract dirt) and raise and lower the jacks a few times to lubricate the seals. FYI, check all the jack bolts--I had several jacks with loose bolts.