I just received a new recoil spring for my P97. After I installed it I couldn't get the slide to lock back. I am unable to force the slide back far enough to catch. When I put the old recoil spring back in there is ample leway for it to retract. The two springs are the same length. The new one looks like it may be heavier and very slightly of greater diameter. Any ideas about how to get this to work?