Avid Juicy 3 brake piston problems I have an 8-year-old old Avid Juicy 3 and I accidentally pressed the front brake lever while the wheel was removed. I used a flat-head screwdriver to reset the pistons. When I spin the wheel after resetting, it works fine, but when I press the lever it  doesn't retract and it rubs against the disk. I thought the oil pressure was the problem and I let some oil out of the system. 


Is this because of the dirty pistons?
is it okay that I let some oil out? (Few drops of oil)


Plus the Avid Juicy 3's piston looks weird and I don't know how to clean it. It's shaped like a cone... (Plus plus, i don't know what kind of DOT fluid my brake uses&nbsp;&ndash;it's green.)
You absolutely should not have let fluid out of the system. If the brake was working before there was not too much fluid in the system. You will need to bleed the brake to remove air bubbles and restore the fluid level. (If the back brake has not been bled in eight years you should do that one too.) Dirty pistons and seals are usually to blame for non-retracting pistons. In extreme cases the whole caliper has to be disassembled and cleaned.

You can try to find the manual for Avid brakes by searching on the SRAM website. There is a 2006 manual which may apply. 

Check out this Park Tool video for how to clean hydraulic brake calipers. It also explains how piston retraction and advancement works.