Thanks Barny, but unfortunately not. The curvy metal part and the squarish button move in tandem, and the squarish metal button has firmly bolted hardware the dictates its parameters of movement. It is very hard to explain and I am sorry I can't seem to find the right words. As I 'lift' the bobbin rubber wheel away from the handwheel, I could either stick a wooden wedge between some of the hardware, or use a very strong small clamp to keep it up and away - but it just seems really odd to me that there is no built-in way to snap it to 'engaged' or 'disengeaged'.