Hi all. Simple problem or so I thought. A colleague fitted two brake pipes and when bleeding he ran out of fluid and allowed air into system and we can’t get a pedal. We blanked off master cyl and got a hard pedal. So cyl ok. No resistance on pedal and hardly any fluid coming out at calipers even when pressure bleeding. I know there is a problem with these if air does get into the abs unit. Why I don’t know. Using snap on Apollo we have operated the abs but still no joy. Instruction not too clear. Do we use this with nipples open or shut. Any thoughts. Cheers. Les