rbernie,
You are correct. I checked my Marlins and the lever does stay locked up and depresses the trigger safety block without pressure being placed on the lever.
I just rebuilt a Marlin 25-36 and replaced the trigger safety block spring and it must be stronger than the plunger spring in the finger lever. The safety block pushes the lever down so that the trigger can't be pulled. I thought my Marlins did the same thing and that was a safety so that the gun would not fire without gripping the stock. It's a good thing that I am not a betting man. So I am going to replace the plunger spring in the lever and make it like the other Marlins.
Nightflyer,
I think you are having the same problem. Just use a punch and push out the pin holding the spring-loaded plunger in the lever. Either replace the spring or try stretching it and put it back together. I think that might cure your problem.