@asvjerry LOL
My DCM Time Frame 2000s date to around 1987 or so. I have owned them for seven years and the still sound crazy good to me. Given the relative rarity of the pair I am reluctant to do much work. It is also the complexity of the design. Twin transmission lines for the two woofers. I have seen the TF1000 crossover so this must be much more. The back panel comes off but it is (no exaggeration) 20 screws.
I also love vintage radios to talk how long a speaker can last. A 1948 Farnsworth Caperhart 114N2 came into my possession recently. These were the finest home entertainment you could buy. In 1948 this model cost 1750. It had Jensen's 5"/15" coaxial speaker the JHP-52. It still sounds great to me all things considered with the cabinet.
I'M GUESSING THAT oops sorry yelling that my ears will deteriorate faster than any other component I own so yay (?) for getting older. BTW Youtube Bobs Capehart 41e 3 conversion if you want to witness a mechanical marvel. 20 record changer on the Capehart that could play A/B, all A than B sides and shut itself off after a preset number of plays.