I don't think the toque convertor is a likely cause for the engine in your 2002 Jaguar being hard to turn. A step by step test to be to 1) Remove the spark plugs, 2) Remove any drive belts. 3) unbolt the torque conveyor from the flex plate. Check how the engine turns after each step. If the engine is still hard to turn after step 3, something is wrong internally and the engine will need to be disassembled to see what is wrong.