I second contacting Ruger. They will install a new cylinder for a very reasonable price.
Two things to keep in mind about revolver cylinders.
First, cylinders found on Ebay or at gun shops and gun shows are very, very often being sold because somethings wrong with them.
Often, the problem is not readily apparent.
Second, revolver cylinders are NOT "drop-in", they MUST be fitted by a competent pistolsmith with the gages and tooling to do the job.
Ruger has new cylinders, all the knowledge and tooling, and will do it RIGHT, for a decent price.