In 2012 I compared a sealed 1971 Howlin Wolf to another original copy that had been played on/off since 1971 (didn't own a TT from 1986-2000).
They both sounded the same (good).
Found the sealed copy @ my mother's house when she was selling it in 2011.
Along with the sealed LP I also found 2 factory matched pairs of Mullard XF2 EL34's, a stack of used RCA 12at7 5-packs (pulls from my old Fender amps) and a small glass vile containing 3 squares of windowpane (the windowpane had turned from translucent to black over a 40 year period).
I gave the windowpane to a neighbor that I had grown up with and tossed the 12at7's after bringing them back to CA and testing them (they all had one poorly testing section).
DeKay