Canon A-1 DoF Preview Lever Problem (?)

Hello, I'm having a problem with my Canon A-1. I recently got an M42-FD adapter and a Helios 44-2 to play with. I know I need to set the A-1 to Stopped-Down AE Mode for the combination to work properly. The thing is, I push the stop-down lever in and it's held in place by the little silver pin like it's supposed to, but I still have to hold it pushed further in for the body to switch to stopped down AE where it only shows the shutter speed, if I don't it just stays in the normal manual mode. I tried using my FD 50mm and the same issue pops up. If I don't push the lever further in than the silver pin it only closes down to f/4 and when I do, normally until f/22. It's not impossible to work with when using the Helios but it's still an inconvenience. Any ideas to what might cause it or if a repair is possible/worth it? I had never used the Stopped-Down mode before, I checked the manual and followed all steps related to it but no help.

Thanks in advance and have a great day!