I had the same problem, a right head banger, I fully stripped the whole clutch system, filed edges, cleaned every part, replaced all clutch seals, installed new Apico dimpled plates & fibres (chamfered all sharp edges) & filled with fresh dot 4 & ELF HTX oil, resulting in absolutely zero change to the clutch dragging issue! Just before scrapping the bike I ended up giving it another go, installed new cork EBC clutch plates, changing the oil to Rock Oil gear pro 75W, drilling a 4mm hole in each of the outer alloy clutch basket fingers & an additional 3mm hole in the inner alloy clutch hub (next to & in-line with the existing hole) the result was best feeling clutch ever, still easy to find neutral after 2 hours of riding, no drag whatsoever, also no slip on the big sections - I run only 4 standard clutch springs rather than 6 for a more progressive feel & it’s a full 300cc!