If one passed the Extra written test in the late '90s at an ARRL test center but did not get the 20wpm endorsement, yet is an Advanced operator, would they now be upgraded to Extra class or do they need to retest? As I stated, I passed the written in the '90s at an ARRL test center.
When you passed the test in the 90's, you would have earned a "certificate of successful completion of an examination" (CSCE). According to §97.505(b), a CSCE is valid for only 365 days, so unfortunately you'll have to test again.
According to §97.505(a), an unexpired advanced license is valid for credit towards elements 2 and 3, so you will need to pass only element 4 to upgrade to extra. If the license is expired the credit is only for element 3, so you'll also have to pass element 2. You must bring evidence of the license to the VE. If you don't have a copy of the license, you can get it from ULS.