Hi!
I've replaced the wiring on some tonearms before. I posted some pictures a long time ago, but unfortunately they are long gone: /forum/imported-unmapped/which-beovox-loudspeakers-for-beomaster-8000
I also replaced the wiring on my 42VF (same tonearm as your 1500). It's pretty easy - you can unscrew the connector for the pickup in front of the tonearm and pull it out. Pretty big solder spots on there.
Connect the new cables to the old ones and pull them through. If the cables are no longer there, route a piece of wire through there first and use that to pull through the new cables.
I used 0,15mm enamelled copper wire, but you can use whatever is thin enough to fit through there.
I've been using the Beogram pretty much daily for several years now - no problems with the wiring.
If you need more information, let me know.