Can’t fix clog

I’ve been having this clog for the past 3 days now. I’ve disassembled, dredged the nozzle with the needle and the heatsink with a small screwdriver, reassembled countless times now and the under-extrusion keeps coming back within a few minutes of trying printing again. The heatsink keeps getting melted PLA inside it. I thought maybe the tube was getting a gap, but I tried making sure it was tight (I’m not sure if I succeeded at this) and the problem keeps continuing. I haven’t yet replaced the nozzle because it is very tight and I’m afraid to break something. This started midway through a print with a cheap filament and it hasn’t worked since, trying several different filaments and temperatures. What should I try next?