Took my Model S&W 1905 out to shoot today for the first time. See here for a photo; https://smith-wessonforum.com/s-w-hand-ejectors-1896-1961/88554-need-info-pistol-grips-1905-a.html

First, I fired in SA mode. Everything was fine. Then I tried DA, and I had several misfires. Come to find out in DA mode the cylinder would not lock all the time, and the hammer was striking the outside rim of the cartridge.

I dry-fired it, and found that the cylinder bolt would not engage the cylinder in DA every four to five shots. This was frustrating, because I checked the revolver out before buying it. I've bought revolvers before, and know the drill to make sure the cylinder locks up tight, and insure it has no excessive play. I mean, this pistol, while the bluing was all but gone, looked mechanically in good shape.

The gun worked fine in SA mode when I tested it in the gun shop. And it worked fine when I did a few DA dry fires--but I did not rapid dry-fire it enough times to discover the problem. After all, I did not want to test the gun shop owner's patience by rapid firing one of his pistols to test it out. I now know to do so in the future.

So I took it back to the gun shop, and the owner said he would either fix it or refund me. He though that the cylinder bolt was spongy, like maybe a spring tension problem.

So from my description, can be fixed easily enough? I know it's a 90 year-old gun, and I hate to spend more on it to fix that it cost me ($135)

I would say it needs a major cleaning or a new cylinder stop spring, or both. Cost = one hour and five bucks along with a few cold ones .