I see a couple on fleabay that match the original one it uses, a Mabuchi EG-500AD-2B.
However, the EG-530AD-2B has the same specs and is far more common. The diameter is 1.3mm less but has the same hole pattern.
Any 12V CCW 2400rpm motor with the right hole pattern and load/torque specs should work, as long as it's not bigger than the original.
The upper motor is part of an off-the-shelf deck from Sankyo (or Shinwa, can't remember which) and has no markings.
You might be able to use the same one as the lower deck, but you need to check if fits and that it spins in the same direction.