Your turntable is capable of very fine performance. The Luxman direct drives from that era are some of the best sounding direct drives made by anyone, which is not the case for some of the later models. The tonearm you have is not stock. It would be fairly straightforward to make a new circular armboard for this TT and drill it for a Rega Rb300 or Rb700, for instance. The turntable itself justifies a tonearm improvement and a good moving coil cartridge, perhaps a Denon DL160 high output moving coil to start.
If I recall correctly, the tonearm and the arm mounting board attachment bolts are accessed from the underside of the turntable chassis. The PD121, PD441, PD444 were particularly well-executed direct drive turntables that also sported clean, uncluttered design, unlike almost all the other Japanese DD TTs of the era. It's worth keeping and putting a commensurate quality tonearm on.
Phil
If I recall correctly, the tonearm and the arm mounting board attachment bolts are accessed from the underside of the turntable chassis. The PD121, PD441, PD444 were particularly well-executed direct drive turntables that also sported clean, uncluttered design, unlike almost all the other Japanese DD TTs of the era. It's worth keeping and putting a commensurate quality tonearm on.
Phil