Well, 12 days after purchase and 5 days not using it, my Goldstar SE has suddenly sprung a leak. 100 BAR gone in 24 hours or so. Imagine the disappointment.
After calming down a bit. I removed the action from the stock and covered the relevant areas in soap suds. The leak was found to be coming from the filler cap area.
I emptied the cylinder and as I was starting to pull off the filler cap, I noticed it was turning quite easily. Kept on turning and the whole gauge assembly came off! All a bit too easily. I figured this was the cause of the problem.
I separated the gauge assembly from the filler cap and re-fitted it using a spanner on the assembly, under the gauge itself. Firmly tight. Re-filled the cylinder, hey presto, leak is gone. The gauge is rotated slightly, but that's OK.
In an attempt to align the gauge, it would seem BSA loosened the gauge assembly during build.
If you find a leak in that area, try tightening things up before spending time and money to send the gun back to BSA. 10 minute job.