Apologies if you already know this Pat, but I guess there will be others that dont. If that technique works for you then by all means continue to do so but did you know that a "manual pre infusion" using the manual group switch does not duplicate pre infusion as programmed in electronic machines? Electronically controlled pre infusion doesn't activate the exhaust / depressurisation of the puck in mid cycle when the flow stops and leaves the preinfused oils in there to continue with the brew when the flow restarts. On the other hand when an operator "pre infuses" by activating the group on/off toggle switch manually, the exhaust / depressurisation cycle of the solenoid valve is activated. That is, much of the disolved oil that you are trying to increase and keep in the pre-infusion, is spat out the exhaust when you stop the group flow the first time, instead of staying in the puck until you restart the group. It cant hurt to do it "manually", but it does not have the same effect as allowing the preset electronics to do it for you by normal use of the touchpad. E61 type groups (whether they be the short manual lever type OR the modern solenoid operated derivative), have a manual pre infusion valve built in to the group that always activates whether an operator tries to do it manually or not, and operators are better served to just activate the group normally as pre infusion is happening regardless. Hope that helps. Rgdz, Attilio very first Crema site sponsor