AR M4 handguard and gas block alignment

[terraformer]

I have a DPMS upper with std M4 handguards and the DPMS gas block. It looks like the gas block moved forward because now there is a gap between the handguard and the gas block, which allows the handguard retaining ring to jingle in a not so merry way. The handguards have started to melt which may be causing issues but I suspect is more of a symptom of the gas block moving.
I loosened up the set screws under the gas block and it does not move despite significant force being applied (no hammers or anything like that, just human power). Now for the question, Is there something else I need to do to move this gas block back into position? How do I tell where it should be lined up to? Is there any way this is actually out of alingment (meaning, am I wrong about the melted tabs on the handguards being a symptom of this)?
TIA
See attached images for reference.

 

[wheelgun]

If you really think the gas block moved, here's one way to check if it's aligned. Remove the bolt carrier group and slide a rubber hose on the end of the gas pipe. When you blow in it you can hear how well the air is coming through.

Another method is to remove the handguards, knock out the gas pipe pin in the gas block, and slide out the gas pipe. Then stick a straw in the gas block and blow to check its alignment.

 

[terraformer]

If you really think the gas block moved, here's one way to check if it's aligned. Remove the bolt carrier group and slide a rubber hose on the end of the gas pipe. When you blow in it you can hear how well the air is coming through.

Another method is to remove the handguards, knock out the gas pipe pin in the gas block, and slide out the gas pipe. Then stick a straw in the gas block and blow to check its alignment.

Thanks for the help. I will try that tonight.