...unless you're positive it's safe for all plastic and rubber parts.
I'n not familiar with this stuff, but a quick glance at the manufacturer's page inducates that this is a pretty strong solvent. Airguns typically use plastic parts in various locations that a firearm would not, and these parts can get destroyed by the wrong chemicals. These parts are not used because the airgun makers are "cheap" (well, sometimes, anyway) but because an airgun is a different kind of machine and therefore needs different materials.
There are 2 plastic washers on either side of the pivoting breach block that provide the normally snug fit of the pivot. It's entirely possible that one or both of these were at least partially dissolved by the stuff you used.
They are not difficult to replace, but unfortunately, Gamo doesn't normally sell these. They might if you ask them nice (but don't count on it!). You will probably need an impact driver (the kind you hit with a hammer) to remove the pivot bolt, though. I've tried wrenches on big screwdrivers and only succeeded in mangling the bolt head. The impact driver yanks 'em right out.
Rich might be able to help you out (peterdragin@comcast.net). Or maybe Bob (CharlieDaTuna@Charter.net) Also, I believe that the same parts from a Crosman Quest (part # C1K77-020, you'll need 2) will work. Crosman's number is 1-800-724-7486.
Meanwhile, check your breach seal. If it's damaged, replace it too (easy to do). This is a Gamo-only part (the Crosman part won't fit it) - but Gamo does sell them.
