I have disassembled and assembled many of these H&R top breaks over the years. Depending on what type of cylinder stop you have will tell you if it's supposed to free wheel or not. If the cylinder stop is a forged part of the trigger, then it will free wheel, as that style doesn't engage the cylinder notches until the hammer is cocked. If the stop is not a forged part of the trigger, then there should be a 'U' shape piece of spring steel protruding through the cylinder stop hole. Often times these small, thin steel springs are broken.

Also, a lot of fault with the lock up with these pistols has to do with the cylinder hand being worn out. This is the piece that protrudes out the back of the recoil shield to lock up the teeth of the back part of the cylinder star. I have replaced a few of these in the past and they are pretty finicky and kind of a pain. The thin piece of spring steel that comes with the cylinder hand needs to be fitted correctly for the cylinder to lock up tight, and getting it to fit properly can take a lot of time. Numrich sells the part, or has in the past.

In the shape it's in with the lock up and the bobbed hammer, I'd offer $50 for it, but no more than that. If you do purchase the pistol, I may have a correct hammer around that I could sell you.