There is no specific idiot section on these forums so that is why I try it here. I have an Isomac millenium 2. It seems to work: hot water, pressure and without the coffee seems to work great. However as soon as I put the filled portafilter literally nothing happens for one minute, followed by a few drips every ten seconds. I use a very fine grind, use the tamper as described and get rid of all the little lumps. Water is not leaking and the pressure seems not to change either. Anybody any advice? Thanks, and apologies if the answer seems so obvious. Gerard

Looks like your grind is too fine. I'd grind coarser and see what'd happen.

Grind coarser. You should see flow in 10 seconds, and get your 1.5 to 2 ounces in another 20.

Coarser grind, possably lower the dose as well. You make no mention on what you are using (grinder/beans/dose).

Yep, coarser grind will be in order.

Sometimes, setting the grinder to choke the machine(like what is happening to you now), is the first step in dialing in your grinder for the specific coffee. The following steps are simply going coarser until you get the right volume, in the right amount of time.*

As Dave mentioned, you can also vary the dose, up or down, to make the shot run faster/slower. So in this case, you would use less coffee.

Only change one variable at a time. You've got: Tamping, Grind Setting, Dose. Keep your tamp consistent. Whether it is 10lbs or 50lbs, doesn't really matter. Just do it the same way every time. Keep the amount of coffee you put in the filter basket the same(your dose). And vary the grind. Observe the change in the extraction, and decide what to change based on that. If you change two variables at one time, like grinding coarser AND using less coffee, you won't know which change gave you the result. Once you get consistent, and feel comfortable to sort of "predict" what changes will do what, then you can try and change two things at once. For now, change one variable at a time.

*I mentioned above, "the right volume, in the right amount of time". . . There really isn't a "correct volume" or a "correct time", for every coffee. Different coffee's will preform best at different extraction times and volumes. You're not going to pull every coffee at 2oz in 25 seconds. Experiment. BUT, as Jim noted above, get yourself in the right ballpark, and then tweak it from there if you wish.