501x shock shafts?

[d16dcoe45]

I just came back from a day of racing my 501x Worlds. First time out with it--absolutely awesome car!! One issue I am having is with the shock shafts. After just one day of racing it appears some of the gold-nitride coating is coming off the rear shafts!! There is definately some silver showing though. Now, I usually replace rear o-rings (on any car) after one day of racing and front o-rings after 2 maybe 3 race days--and that keeps the shafts scratch free. But to have the gold come off on brand new o-rings seems a little strange to me. Any one else have this problem? Are the stock (non-worlds) shafts better? For some reason they are a bit shorter than the worlds shafts. What about the Yokomo gold shafts--which ones do people use? I love the car but I don't like the durability on these shafts--otherwise the shocks are great, super smooth with the Worlds low friction rod guides.

Also, when building my 501 I had to ream the holes larger in the bottom shock cartridges (where the o-rings and rod guides are held) otherwise the shafts would actually contact and bind on the hole ID!! I have never had to do this on Losi shocks which have a very similar screw on bottom cartridge. Have you guys had to do this on your 501x shocks? I am wondering if the shafts wore because I didn't ream the holes large enough--doesn't seem likely but I suppose its possible.