It does not matter if you get bubbles at the bleeder valve, as long as you are moving fluid, which is what it's about. Bubbles at the threads are not in the line. Although I use a OTC air-powered vac bleeder that moves fluid quickly, I always have bubbles at the bleeder valve, but all the air comes out of the lines. Yes, a tighter seal helps move the fluid quicker, but don't worry about the bubbles after you have moved at least a 1/2 pint of fluid, or whatever it takes to fill the line, and cylinder, which shouldn't take quarts of fluid to bleed. I usually just suck a quart, or about a pint on each corner, and finish with a pint on a complete bleed. I do it all by myself, with no helper needed, and it has worked many times now.