Shoot a sheet of paper at 10 yards with some #6 dove shot.
Remove the sight. Replace the sight. Shoot another paper target with the same load.
This will show you that it does hold a zero. Mark the top of both sheets.
The battery is said to last 10,000 hours. You are about 210 hours into that.
But batteries are cheap. Some say the original battery is not as good. Batteries have about a 10 year shelf generally. Use it this season then test the battery.
Cut it on and check it every day until it is dead. It should take a while. Then you can report to us.