Yes,your suspect is realty ,or new cartridge , no second hand , for U.S . much money  but  no problem or you must modify tonearm for a TP4 cartdrige.YES   is a complicate work  for dismanteling ,recable and rebalance tonearm but is  possible and no problem in future for change needle  , otherwise change a turntable with normal cartridge  , i have make this modify for a BEOGRAM 5500 many years ago a nightmare and for normal tonearm magnesium black in this time for a beocenter 4600 and 7002  yes  is orrible solution but play very fine   sorry for my little english from Italy