I recently went from a Cairns 1010, to a Cairns New Yorker leather N5A, made in 1987. Size medium. The helmet was a little big so I had adjusted it to the smallest it can go, but it was still a little loose. So, I ordered some foam adjustments and placed them in the play spots, and with my flash hood on the helmet fits perfectly. But, the problem I'm having, is when I have a mask on, the helmet fits all nice and snug & whatnot, but because of the mask, the helmet sits just a little higher, but not even much higher than it originally sits without the mask, and the helmet constantly slides up over my forehead very easily without very much movement at all. It's extremely annoying, and it has a big affect on some things I'm doing hands on. I've spent hours adjusting the chin strap, and everything else possible but nothing helps at all & The brim is only a fingers width apart from my ears, so its not sitting too high at all. If you have any suggestions or advice to help me even the slightest it would be very much appreciated! Thanks!