Some GTO owners have had problems with the key not turning the ignition switch.
Here is the GM Tech. Service Bulletin No. 09-02-35-003.
I'm fortunate I guess, because the former owner of my Goat had this problem just before he traded her in, and a new one was installed. So I should not have that problem for awhile. If you have the problem there are a couple of ways to go about fixing it. Some have removed the Ignition housing and used a dremel tool to smooth out the bump on the ramp, caused by the hard thump you feel when you remove the key. The original part that came on our Goats is very soft, and prone to excessive wear in no time. My GTO had only 26818 miles on her when the problem happened. High temperatures, like we get here in Texas, seem to contribute to having this happen. Unfortunately I don't know if when they changed the lock cylinder they replaced it with the old part (which will be prone to having the same problem) or the new one. If you have not had the problem yet, and the ignition lock cylinder has not been replaced, You need to be ready! The new part supposedly has been upgraded so the metal does not wear away like it does on the original. Most of us don't have warranty any more, so if you have to pay for a new part, make sure you get the new style lock cylinder.
Part numbers:
Old style: 92172018
NEW STYLE: 92234035
If anyone here has done the dremel mod, or replaced the cylinder and has photos, please start a thread about it. This is something that all of us will go through at some time with our Goats, so please share your experiences with this. We need more DYI threads here on GasTiresOil.com, so if you do any mod, please take photos and start a thread about it.