How to clean a nozzle after trying with guitar strings doesn't work?

It used to be that I could feed PLA in by hand and extrude a fine line without too much force (5 lbs?).

Now, after cleaning, I get 2 seconds after great force (10+lbs), then it won't flow, despite a bunch of hand-force on it (180C like before). Blue PLA from the startup kit (like before).

To clean, I took out the Teflon liner, and pushed the PLA inside it out with a 1.75mm drill bit (butt end - it came out without needing to bore it), use a 3mm drill bit while the tip was hot to gently grab the remainder of the PLA in its flutes at the tip of the bit (then the Teflon liner goes back in easily), then use a B guitar string to clear the hole (easily either way though it's harder to line up going from outside in).

I was running ABS, so I tried cleaning with acetone first (that made it so I could blow air through it when it was cold-- evidently I had some ABS still hanging on)... but wanted to see if I freed up the nozzle, so I've been trying the blue PLA ever since...

I can blow air through the nozzle when cold (rocket air bulb for cameras).
I can blow acetone through it as well (though acetone gets pissed when the temperature is on).
I can extrude with great force for 1-2 seconds (PLA or ABS), but then it just quits... so I don't think it's worth completely reassembling and putting back into service yet...

I haven't taken the PEEK off the brass yet (I thought the guitar string would do it)...

Aand... how tight should the setscrew be against the Teflon insert?
I've been tightening 'till my Home Depot Husky screwdriver (1AAA battery) stops...

So... what should I try next?
Lye+Methanol soak (I bonded the thermistor with JB weld... izzat going to kill it)?
Acetone Soak?
Pull apart and put into self-cleaning oven?

Give up and get a new hotend (E3D on order -- but that's why I was using ABS -- to print the fan bracket)?

 

It looks like sometime during the above, I damaged the PTFE tube -- I changed that and it's back in service... I need to find a place to buy them b/c they seem to be expendable to me

I have, however, put the hotend on a Molex Mini-Fit (from a 12V ATX extension), so now I can swap/clean the hotend much more easily.

Anyone know where I can get a bulk order of PTFE tubes?