[MadMax]

Bleh. Pistol trigger internals should not be lubricated. Goopy trigger bits can accumulate abrasive sand and dust which generates a coating of what I call GBB smegma. Truth is, silicone oil altogether is a crummy lubricant. It has no retention properties and will spread to a molecular thin layer which offers no high pressure film protection to metal on metal contact. The only reason I offer it in the GunGas kit is because it is inert and good for conditioning rubber parts. The very low viscosity usually blasts out of the barrel instead of collecting into a smeary fouled coating.

Inadequate lubrication is almost never the cause of mechanical failure in GBBs. Usually something more explicit has gone wrong. Judging from your first symptom of gas venting with no slide movement, I would guess that an important valve in your nozzle body wasn't working right so it would not shut off breech flow and switch into blowback mode.

After a disassembly and cleaning you might have gotten it working right or it it got unseized just by moving things around. I still suspect the reed valve (if it exists) in your nozzle body. If it's not pushing forward and closing the breech flow it will not direct gas to the blowback efficiently.

I'm guessing that your GBB has most of the operating principles of all other GBBs.

As to your bad fill valve, try jiggling the stem around with your adaptor tip a bit. Sometimes valves seal up with a bit of manipulation. You can also try a drop of lube in your propane adaptor to wet the gas a bit on your next fill.