Robti - Didn’t pay much attention then…. :-)
From Coffeetime (http://coffeetime.wikidot.com/backflushing-how-do-you-do-it):
“If the solution was particularly dirty (or the foam coming out of the group does not turn white, but stays brown), you may want to repeat the whole process, unless the instructions with the cleaning product advise against this. Your Coffee Brew lever may squeak and become stiff while doing this and although this is only temporary, I recommend you use a suitable food safe lubricant on the cams in the E61, see e61-lubrication. Pull a shot to “cure” the group, some people say to throw this away, but that’s up to you and how frugal you feel.”