I was going to send mine in to Air Venturi for servicing, but UPS wanted over $120 to ship to AV. Decided to try DIY. I just hope I don't have to send AV a bag of parts to reassemble!!
There is a place on eBay UK that has kits for air arms. They list an email address ([email protected]). I would send an email and ask if they have kits or sizes for the regulator. No charge to ask…
I have a 5 yo S510 xs .177 rifle that I am going to reseal. Did you happen to find the correct size of the regulator orings? I have look everywhere like you and nothing.