If it can be taken it apart and there are no metal pins on the parts, you can leave the parts in a bath of detergent overnight. I have a bottle of degreaser and seal-able containers for this purpose. Also great for removing mold release grease from parts. Stickers will just float off.
To tighten screw holes grab some superglue and a pin. Use said pin to apply glue inside the hole, wait for it to dry and screw in as normal.