Corny keg safety valve question

I have a 10+ year old corny keg. Except for one thing, it is in great shape. The one issue is that the plastic thingy underneath the lid that is the inside part of the safty valve is deteriorating (plastic is crumblig). Because my beer contacts this plastic when the keg is moved or sloashed around, I am concerned about sanitation and pieces/bits falling into the beer and being consumed. So, it appears my choices are to buy a replacement lid or replace the valve. Online, I am only seeing the outer key ring-spring thingy as a replacement part - is this inside plastic thingy also replaceable and available for purchase? If so, what's it called and who sells them? Or should I just buy another lid?

depends on the type of prv.

here are some http://www.simgo.com/replacem.htm

Could this be the one you are looking for, it says its for a pin lock lid (are the lids different on pin lock vs ball lock?) http://www.chicompany.net/pin-lock-pressure-relief-valve-773.html
double check that is what you want though.

Most lids don't have an inside piece that the pressure release valve screws into so it's harder to find those pieces. When I bought my kegs a couple weeks ago two of the lids had those types of lids. The inside piece looked pretty grungy on mine too. Luckily the person I bought them from on e-bay was local and let me come by and switch out the lids (they were running a soda company so there was plenty of kegs to mix and match with).

While I was sorting the problem out I found that some companies that were selling the lids for more money than I paid for the entire keg. The best prices I found though were from this company: (I haven't dealt with them so no promises).

http://www.chicompany.net/ball-pin-lock-kegs-parts-1/ball-lock-keg-parts-3/lids-89/

Thanks. Looks like I am going to need to investigate this more. The cost of replacement lids is pretty high. I guess I need to see if I can even screw the existing one off first.

Did a little investigating into this. This is apparently and older corny design and the grey plastic nut that holds the relief valve assembly inside the lid are not made anymore. The folks at KegConnection tell me that they order an aftermarket replacement nut from a manufacturer to retrofit these older kegs. I am hoping to get one from them in a few weeks to test it out. FWIW, I also read that this older plastic nut design is supposedly responsible for the vast majority of gas leaks that occur around the relief valve (rather than the lever/spring mechanisim on the outside of the lid).

CHI company is great to deal with. They are fast and take care of any issues right away. At least that's been my experience with them.