Re: Sticky G# key
It really depends on why it's sticking. Is the pad actually sticky? If so, then try to clean it with ungummed cigarette paper or a dollar bill. If that doesn't work, have the shop replace the pad.
Is the tone hole sticky? Clean it with a damp cloth--then dry it.
Is the tone hole rough? Ask the tech to smooth it, or try it yourself with an emery board. I wouldn't use a file, too easy to wreck the pad.
Is the key bent? If so, the tech at the rental place will need to fix it. (If you try and break it, they might charge you for it.)
Is the spring sprung? If so, hook it back around where it's supposed to go.
Is the screw rod not all the way through the rod? Then make it so.
If something is bent, don't try to bend it back, let a tech do that. It's too easy to break something that's been bent out of shape.
Hope this has been helpful.