I was slightly bored and decided to try and macgyver something to replace the broken SS tube.
I took a cylindrical ceramic fuse, attacked it with a torch (yes, i really like to torch things) and removed the end caps, ending up with a ceramic tube with a cca 3.6mm internal diameter. I've epoxied that to the lower threaded block that screws into the nozzle, but first, i've sanded off the remains of the tube and used a rotary tool with a conical sanding attachment to give a slight fillet to the hole in the block (reasoning being that should reduce chances of filament getting stuck on the edge on its way in, due to different IRs of the block vs. the ceramic tube).
Then i took a big, chunky washer and epoxied that to the middle of the tube, to increase its surface and act as an additional heat sink. The internal diameter of the washer was much bigger than the external diameter of the tube, so i've filled it in with epoxy. I've been using thermal epoxy for all of this, in case of the washer, with a slight more filler than normally suggested (should be 1:1), hoping that would increase the thermal conductivity at least a bit.
Finally, i've epoxied the tube to the upper screw block, while taking care not to mess up the threads (unlike the lower block, the upper screws inside the heat sink all the way).
I honestly doubt this will work, because of two factors - the epoxy doesn't stick that well to the ceramic tube (it flakes off, i tested it first on another tube, but didn't wait for it to cure all the way from gel phase); and the tube's internal diameter is much bigger than the filament, meaning lots more space for it to bloat and get stuck, if the heat creeps too far up the tube. But hey, like i've said, i was bored and trying can't hurt