I just finished servicing and cleaning up a badly rusted Gecado 25 for a friend. It was his grandfather's little rifle, so a lot of sentimental value.
Mechanically the rifle is in very good condition. The leather piston seal is still very good and the insides wasn't totally dry and chalky yet.
However, the barrel and tube outside was badly rusted. It also needed a new mainspring as it was only giving 420fps over the chrony. Fortunately I had a spare spring of correct dimensions that just needed shortening.
After a huge amount of elbow grease and tlc the rusted surfaces are now cleaned up and slightly blended using some cold bluing. The rusted sights also cleaned up and cold blued.
With the spring replacement it's now running at a respectable 570-580fps. I'm happy with that.