Loose radiator connection

[Quinla01]

Whilst investigating air in my hot water system / tapping noises from a radiator I noticed the return connection on the radiator isn’t fixed.Where the valve goes into the radiator just slides back and forth to the point I pulled it a bit far and water started coming out. Could this be the cause of air in the system? Is it just a case of tightening something up or is more work involved?
Thanks in advance

 

[ShaunCorbs]

Looks like an adjustable rad extension

 

[Quinla01]

Looks like an adjustable rad extension

Oh so it’s meant to move back and forth? What about the water dripping when I pull it back about an inch?

 

[ShaunCorbs]

Yes and no sounds like the oring has gone