Gee, Harry, sometimes you say things that are accurate then you post something confusing and full of misinformation....
Deluxe 71s ALL had an inlaid swivel base on the buttstock and a swivel eye machined into the fore end cap....None had any sort of front swivel eye on the magazine tube...the swivels were the same Supergrade type as present on SG Model 70s and M52 Sporting Rifles along with other Deluxe Winchester levers such as 64s and 65s...occasionally, for some unknown reason, the swivel would not fit into the swivel eye, probably due to the eye's orifice being undermachined....
The OP may indeed have an aftermarket swivel eye attached to the magazine tube and, if so, simply replacing said eye will solve his problem. IF he has a Deluxe with the swivel eye on the fore end cap, he is in for a devil of a time, finding a replacement cap/eye....
A 'smith could fashion a replacement eye and weld, not solder, it to his existing fore end cap then reblue the cap. That may be his best option if he has a Deluxe....if he has a Standard that someone put a swivel on the magazine tube, simply replacing the broken stud is an easy fix....if he's in the Allegheny County White Oak, Economy Gunsmithing (724-266-0232)) can fix him up....
I have never known an eye to "break" on a Deluxe fore end cap but I suppose anything's possible....