I design all of our pneumatic and hydraulic cylinders where I work. They are used in the plastic injection industry, where environmental temperatures are 300° to 550°F. My experience with O-ring manufacture Parker is, any O-ring whether it’s a cup seal, poly pack or x section O-ring, all must have some kind of lubrication during assembly to avoid damage. Also proper installation leads (chamfers) for seals also help prevent damage.
By the images and the descriptions of problems, it sounds like FX may not be lubricating the seals for installation. Based on the image at the top, it looks to me as the regulator body may not have proper seal leads for installation, hard to tell with image. Less likely issue is proper clearances and surface finishes between mating components, will also cause leaks and damaged seals.
Another thought for those that try to replace the failed seals on their own. Most seals do not like petroleum based lubricants (if you use lube). So be mindful of the seal material and acceptable lubricants for that seal. If using lubrications, I would be worried about propagation of the lubricant into other arears of the gun, that should not have lubrication, thus cause something to get plugged that should not.
Just my thoughts. Thanks for the post, gives me things to watch for, when mine comes in. The information I provided above, is for those that may not have a lot of seal knowledge that is based on my design experience what that seal manufacture. Hope it’s useful info. I make no warranties or guaranties.