One of the inner CV joints from my Synchro is sitting on the kitchen counter.
 Question:   Could someone tell me how much wear is acceptable before one
replaces the joint?  There is no rust, pitting or other damage other than
"grooves" or "depressions" where the balls have been riding on the outside
race(does bearing terminology apply to cv joints?). The wear grooves are
distinct--they can be seen and felt.

Thanks.  Dan