I am losing my damn mind trying to get the basket/portafilter to fit into the group head when the machine is hot. Sometimes it works with just a little grunting and counterweight, other times I turn the machine off and walk away with no espresso at all. At first, I assumed that I had put too much espresso in the basket. After a few more struggles involving sweating and swearing while trying to get the portafilter to turn to the left, I decided to apply a little more scientific deduction to the problem.

Here are the clues, who can solve my mystery?

When the machine is cold the basket/portafilter fit together like old friends.

When the portafilter and empty basket heat up with the machine and then are removed to fill with espresso, you can more or less forget getting it back on.

If the portafilter/basket do not heat up with the machine, you have a fighting chance but no guarantee.

Today I couldn't get even a cold, empty basket in there.

My conclusions so far - physics. When metal is hot it expands, hence the (somewhat) better chance of getting a cold basket/portafilter on than a cold one. Potentially the metal of the group head is also expanding and therefore making even an empty basket feel inadequate? But if this is the case, a. why is this just becoming a problem in the last month when we had been making espresso with relative (it is a LaPavoni after all) ease for the previous five months and b. it seems unlikely to me that the good people of LaPavoni made a machine that expands so much when hot that you can't get the damn basket in. So what am I not seeing here? Is this a "newbie" problem with an easy fix or is something bigger going on?

Thanks in advance for any suggestions, ideas, or explanations to our mystery!

Are you sure this machine has the correct portafilter-group gasket? (Usually an O ring, sometimes a square ring.) With the machine cold and no coffee in the basket, how far can you turn the portafilter? Try it also with no basket. I have noticed that some dispersion screens are slightly thicker than others. The same is true of portafilter baskets. Early 2nd generation groups seem to require a much thicker gasket than later ones?

You can take out the gasket. You should then be able to turn the portafilter all the way until it hits the boiler! That will tell you if your only problem is the wrong O ring or square ring gasket.

There was a post a couple of weeks back where someone couldn't get their PF in. Turns out the piston had unscrewed a bit from the piston rod. I can't explain the temp differential aspect, but it's worth popping the dispersion screen off and making sure the piston is fully screwed into the rod. You may have to really torque it with your fingers to see - even if it's not obviously loose on there, it can have an impact.