Hi,
I wonder, while not pulling shots (I only do twice a day normally), my instincts tell me to leave the portafilter unattached. That, to improve the gasket longevity.
However, I find out that it sometimes is very difficult to attach the portafilter to a cooled machine, where it seems that the gasket has expanded or moved downward.
I would appreciate your opinion on this matter
Thank you

Leaving it attached has worked well for my five years of LP ownership. Not tight. Just snug enough so that it doesn't fall out.

I always replace the portafilter in the group. It performs multiple functions, like group cooling and a stable group idle temp at pressure. It also helps keep what you are facing from happening as often.

I think your issue has two parts. First, yes the portafilter is meant to be replaced in the group, same as with any espresso machine. Second is a possibility that your piston is hitting your shower screen at bottom and pushing the screen and gasket out. Easy check. When group is cool, place fingers on shower screen and raise the lever a bit and let it come back down. If you feel anything at bottom of lever you will need to adjust the nuts on the top of the piston so that it does not hit the screen.

I only have my machine for three months now, but I'm leaving my portafilter unattached, too. Prior to switching the machine on I put it back in so it gets pre-heated, but after pulling my shot(s) and cleaning, I leave it lying in front of the machine. In the first weeks I found the portafilter pretty hard to attach, just like you described, but now it usually works rather smooth every time.

The PF gasket lasts quite awhile. I would guess that you should get a few years out of one. I've never kept track, and I've replaced mine a few times in the last 20 years. FWIW I always put the PF back in the group.

Piston gaskets need replacing much more frequently if you don't regularly lube them. In the first 5 years I was replacing my piston gaskets about twice a year before I realized that the lower gasket gets more wear. At that point I was able to get a couple of years out of the upper gasket, and the lower ones lasted 6+ months. Around 10 years ago I started lubing them every couple of weeks when I roasted beans. I have only replaced 2 lower gaskets in the last 10 years, and no upper gaskets. After a discussion awhile back on this forum about lubing the piston gaskets I did some tests, and found that I could push it to 4 weeks with no difference in performance. So, now it's been awhile, and I've been lubing the piston seals every 4 weeks with good results. Lubing the piston seals takes only a couple of minutes, and does not require pulling the piston.

jtrops wrote: Lubing the piston seals takes only a couple of minutes, and does not require pulling the piston.

How exactly do you do that?

1. take off the lock nut, and jam nut from the piston shaft (above the lever fork)
2. use the lever to push the shower screen down. It won't completely come out, but...
3. Remove the pin that attaches the lever fork to the piston shaft
4. push the piston shaft down to free the shower screen, and expose the lower seal.
5. lube the lower seal, and push the piston back up into the cylinder.
6. push the piston up, and down a few times to get lube on the upper seal.
6. replace the shower screen with the portafilter
7. re-attach the lever fork to the shaft with the pin.
8. set the lower limit of the piston with the jam nut/lock nut

Done!

Edit:
I found the vid that I made a few years ago.

Great info, thank you very much!

I usually just pull the whole group apart when lubing and just give it a good clean as well. I was doing so monthly but lately more like three weeks. I changed to the silicon gaskets, and they seem to want lube more often.

Definitely going to try your method in between cleans.