Try the cleaning method where you heat up the hot end then lower it to the plastics transition point and then pull it out to clear the clogs. Also just pouring acetone down it wont help.. it takes a While for acetone to disolve abs. I'd suggest disassembling your extruder and using abs + tools to clean it manually.
Having said that it's hard to tell from that picture. You could have a permanent clog which can Only be cleaned manually. Someone also suggested brake cleaner.. havent tried it yet but the stuff will disolve ANYTHING. You didnt mention the type of hotend though. I use all metal (2 x e3d) so theyre safe to clean with anything. If you use a partial plastic one thats a whole different thing.
