Problem with Joker 1/4 Enterbay

[ms.sorry]

Hello.
Have a problem with a gun (look at pics).
Bought Joker 1/4 (Enterbay) recently and saw that that the gun is broken..
Question: Some detail was lost or the fixture was broken off?
Sorry for English.

 

[ebor]

That piece slots into the rear area of the gun, look for a hole to slot it in.