ok thanks, i have had a look and the amal valve has been removed. i am trying to get it on the rollers this week to get it set up again. it is definately like its holding back rather than cutting out, it boosts really hard in 1st,cuts out at about 0.8 bar in 2nd and boosts to just over 1 bar in 3rd,4th and 5th but doesnt seem to pull very well.