There was a post quite recently advising not "tickling" the tickler but simply pressing it down until a very small amount of petrol comes out the hole. Since reading that, I've been employing the technique rather than thrashing away like a maniac at the tickler. It works fine and I can only assume will cause less wear over time. Don't know if ti will help this current issue but worth bearing in mind. The whole float/float valve area on the monobloc isn't the greatest design ever anyway. I had endless issues with my 5Ta's  375, replacing floats valves etc. I discovered that I'd been over zealous with the fibre washers and placed one between the carb body and needle seat which led to overflow problems. Can be bleedin' infuriating Hopefully, it's something simple and easily sorted out for you, Stu.