From the Ideal Grade and up, the roller release was used on shotguns starting around 1919. Hunter Arms knew there was a problem with for-ends fallings off non-ejector guns before 1912 and used the Curtis for-end release (a button on the end of the for-end). This was a costly thing to make and after 1919 (approx.) they started using the roller release on non-ejector guns from Ideal Grade up. The Field Grade was on it's own.
Since this gun has the roller release, there is a good possibility that whomever did this work did not put the notch on the back of the loop and so there is nothing for it to latch-up to and it is not holding it on, just the "J" spring is.
The best thing to do is take the wood from the for-end metal and try it on the gun. You should be able to see if the roller is catching or not catching that notch if there is one there. If it will not work, I'm guessing it isn't there.
