http://www.gunsprings.com/Rifles%20%.../mID120/dID332
The link above is to Wolf Springs.
The Winchester 75 and 69 used the same basic bolt. Thus the spring may (should) be the same. I would call Wolf before ordering.
If the above does not solve your problem and you have a worn out, but not broken spring; you can stretch it a bit, and then heat treat it and temper it again. The foregoing does require more metalworking knowledge and skill than is possessed by the general population. However, you can likely find directions on the Internet.
Hope this helps.