The TT2400 is a very nice Turntable and pre-dates the Chinese OEM rubbish that the company churns out now! The decks were built in Japan and used a special version of the Jelco SA-250 arm which had a cartridge connector with 5 pins - the fifth pin in the centre was a DC voltage supply to a special headshell that had a flip-down light in it.
At the time of production, the deck cost about twice the amount of a Technics SL-1200 so not many were sold. Pehaps that is why the model number is twice that of the SL-1200. Manufacturing stopped in the early 90s and the leftover parts apparently went to Vestax who developed them into the PDT4000/5000 series a few years later.