[1967 4K]

I replaced my 67 disc brake MC back mid summer and had hard time bleeding my front four piston calipers. Was advised that in most cases depressing the little button on the back side of the round device ( sorry don’t know proper name of it) that is first downstream from MC wasn’t necessary.
I remembered depressing it years ago when first putting brakes on the car in 1995. I made me a small wooden wedge cut from a 2x4 and pushed it between the button and the booster.
Debbie n I went through the process and everything changed. Got good solid fluid flow and the pedal felt as it should IMO.
I’ll enclose a pic of the round device and my wooden wedge. Bleeding brakes can be a pain sometimes and I was getting frustrated till I did this.