I just got a S&W M10-5 and it has a problem...

It didn't when I was looking at it, but now once home with a closer inspection, it does. Here is the issue, 85 % of the time it works great.

15% of the time when the cylinder lock drops it quickly jumps backup and the gun seems jammed. Since the lock re-engages the cylinder before it rotates and due to the fact it is in the locking groove - locked in, the gun wont cycle. Usually when it jams it just catches the tip of the lock and isnt fully in the groove. I don't want to force anything, and the grooves on the calendar seem undamaged.

This problem occurs when the gun cycles - both single and double action.

I need feedback....

From quick reading and looking at it, maybe it is the spring or the actual cylinder lock? or is the timing totally off & it needs an overhaul.

Here is the bad part - I am in Canada and we have draconian gun laws and this thing needs to be fixed north of the 49th due to all the paperwork that would be required to have a real US smith work on it.