If the cylinder latch is difficult to activate, there might be a small burr somewhere causing the problem.
I have a vintage Police Bulldog .38 with the same problem. Charter will repair the older revolvers for a reasonable fee, so I would recommend sending it to them. That's what I'll eventually do with mine.
Where I live, very few gunsmiths work on Charters, and most lof the local gunsmiths cost an arm and a leg anyway. If you can find an "old timer" gunsmith with reasonable prices who isn't afraid to work on a Charter, you can go that route.
I did happen to find just such an "old timer" gunsmith who fixes little nitnoid things on revolvers for what is usually a $35 fee. By comparison, the other gunsmith in my area charges a $40 upfront fee to even take the gun in for work, and then costs $75 per hour after that. It pays to shop around.