I've just looked at eta docs and this washer is part 2753 (indicator distance piece). Have you ever seen an a7750 with this part? I'm not sure why they don't use it. It simple to make and install and it would make problems with days wheel gone.
I'm aware why day wheel is popping out. I spent some time testing this and it seems that it would pop-up easier when using quick date change then when turned by day change wheel.
Regarding hands removal process... Yes this is how I worked so far but I find above tools hard to use in this way. 'Forks' of presto tool are sometimes too thick to be put between hands and I risk damaging the hand below with presto tool. (I'm also using bergeon dialog protector.)
What tools do you use for removing central and subdial hands? Any tips?
Another thing, putting the hands back... I found using pegwood with small amount of rodico at the end the best tool for mounting subdial hands so far. I find it difficult to mount hour hand as I lack the proper tool. I have a cheap anchor hand presser, which is fine for minute and top chrono hand but useless for pressing hour hand. Right now, I'm using plastic tweezers for pressing hour hand which is far from good solution...