This is the well known problem of Linea. In my 2-group FB70 and even with big grinders the problem of warming groups is the same. Eventually, the third shot is good .

My solution after testing with a scace, then realizing flushes without the resistance of coffee in the basket was giving different results...(the scace orifice mimics the flow rate during an extraction) I drilled a blind filter with the smallest number drill (not an easy feat without breaking the drill against the stainless blind filter).
I think I ended up using the #79 drill because I broke the #80, so I have a .0145" hole in my blind filter basket. This solution works very well, without burning through coffee to get the group stabilized.

Recommend upgrading to a large conical, lots of choices available for much less $ than a Robur, my Macap cost around $850 on a year end deal.

The solution with a drilled blind filter seems to be efficient enough. For me, much simpler is to make just another coffee shot, without changing filters.

After a few years with Linea, sometimes I am looking jealously at any simple HX. Many times I have received excellent coffees from very basic Wega or Elektra. Linea is cool, but...

mitch236 wrote:Well, I certainly don't want to spend $3400 for a Robur!!! I can't imagine it would improve my shot consistency enough since I only make one drink a day during the week.

Yes, it will. I have used/owned a mini, super jolly, kony and robur. Huge difference between the Mini and Robur, or other big conical grinder. There are simular differences between the Mini and other brand conicals or large flat burr grinders.

cannonfodder wrote:Yes, it will. I have used/owned a mini, super jolly, kony and robur. Huge difference between the Mini and Robur, or other big conical grinder. There are simular differences between the Mini and other brand conicals or large flat burr grinders.

Well I will find out soon! My Robur arrived today!! I will be seasoning the burrs then its go time!!!

I found a Robur E for far less than $3400 so I couldn't refuse!

You are in for a good time. You will be surprised how easy it is to pull consistent shots with a little basic technique. Once a coffee is dialed in, you will rarely have to adjust the grind and the clarity in flavor you will get in the cup will be eye opening.