4 speed slipping out of second gear

The two pictures in the previous posts don't show it, but there is a hole just above the shift levers, that is the alignment hole. Choose what ever size pin into and through the shifter to align the levers. As others said , make sure the mounting plate is tight, the shifter and side cover levers.
If you have the orginal Hurst Mystery shifter, there are no bushings in your shifter or side cover levers. If they are worn, I don't see why you couldn't drill them to size and use the Hurst Competition plus shifter bushings. I could be wrong on that, maybe someone else has installed them on a Mystery shifter.