Shower outlet elbow

[realmil38]

Help! We bought a 3 way concealed shower valve with diverter. The water feed to the handset is via a outlet elbow fitted on the wall. It has blown off and water came pouring from behind it.

Has anyone experience in fitting these?

 

[PlumbBobBob]

strange it blew off they are usually screwed on, onto a bush or fitting like this

 

[galaxy_plumbing]

is it one just pushed on and secured with allen screw?