I have a 2011 Shot Show Winchester M1885 in 45-70 in great shape. It was just pointed out to me that the trigger will not go to half cock. The gun is used but new to me. Any idea what the issue may be? Thanks in advance for ANY input!!

Don't believe it has a half cock notch. Has an inertial safety; if the hammer hangs up or slows for any reason, it will not fire. That substitutes for the half cock notch.

Because of this, these have to be kept very clean to be reliable. And, they're an incredibly hard puzzle to put back together if you disassemble. After some experience, with the help of some slave pins, it's possible, but difficult. So, keep it clean by spraying it down with silicone spray or similar, and re-oiling. If it gets real dirty, I pour turpentine through it, and then re-oil.