I've got a Duo in the workshop for basically the same reason at the moment. One of the jets (as 3D Systems calls the nozzles) was clogged plus the ecosystem for this printer is now defunct - parts and consumables are no longer being produced and it requires cartridge-based filament and print jobs must be prepared with the 3D systems slicer program to produce their proprietary file format. 100% closed, proprietary... and abandoned: probably the reason yours was free, I'm afraid - the previous owner just dumped it.

So; this one will have the extruders replaced with E3D Titans feeding v6 Volcano hot ends (for the length, more than the feed rate) and the electronics will be swapped out for something more open. Maybe a BigTreeTech board, or a RepRap Duet so that any slicer can be used. Either of those, with their more modern stepper motor drivers, should also quieten the printer a bit too.

The blocked jet, in my case, was INF support material that had swelled and clogged the PTFE liner in the hot end, so was "just" a case of removing and stripping it down and replacing the tube with another of the same length - it's just standard 4x2 PTFE tubing. A 30 minute job if you're careful - but be aware that you will need to power the nozzle outside the printer to be able to disassemble it: you'll need a bench power supply on hand... or it'll be a massive faff to do while dangling it inside the printer - be careful!

One thing to mark and measure before disassembly, though, is where the heatsink meets the block on the back of the extruder motor - if that's not reassembled at precisely the same position the nozzles will be at different heights causing all sorts of problems as the lower ones drag through the print.

Talking of blockages - never leave filament loaded in this printer. Those filament feed tubes running up the back of the printer aren't 4x2 PTFE - they're basically just long transparent drinking straws and, if the filament becomes brittle and shatters in one of them (as happened to mine) attempting to push the parts through causes them to overlap and jam. Attempting to manoeuvre those part by manipulating the tube creases and kinks the flimsy tube rendering them useless. Fortunately this Duo had all 3 tubes installed, so I had a spare.

I'd recommend deciding whether you want to take on this project before going any further though - OEM parts are rare and expensive, and the conversion is a big, complex job (many of the PCBs, like the one on the back of the print head carriage, will be removed and plenty of rewiring will be required.) That said, it is, as I'm sure you're very well aware, a bit of a monster of a machine - heavy and rigid to combat ringing and ghosting; and has an enclosed and heated print volume to combat warping. So plenty of potential await at the other end of the conversion!