Rebuilding Front Girling Calipers, these pistons useable?

[ChefSkinny]

Both sides have this same corrosion on the top and inside. Are these still ok? No pitting / blemishes below the first o-ring groove.

Also I can't get one side to pop, the first popped out in less than 1 second, the other side is being more difficult. I don't have a spare brake line around to chop and use though... Any tricks?

[ChefSkinny]

also does anyone know if you can buy the rubber boots that cover the guides? all of mine are cracked. I've also got some rings on the sleeve, they look like they could be machining marks, is it normally 100% smooth?

[jlevie]

The only place on the piston that matters is the side of the cylinder where it slides on the o-ring in the caliper. If that area is free of corrosion the piston is good.