-
Assuming you mean the Gaggia Factory, not the spring levers, I used The Espresso Shop for service parts and found them great, especially with the fiche diagrams.
-
I use theespressoshop.co.uk
The postage is a killer, but OK if you remember to buy all of your bits and bobs at once.
insulation spacer that I've seen people fit between the group head and the body
Everything I've read says not to bother - the heat transfer through the metal is negligible when compared to the heat that comes from the water.
I did upgrade to the brass boiler pipe connector, though, as the plastic one falls apart. I alsonwrapped the neck of the group in PTFE tape.
If you want an insulation anyway, eBay is your best bet, as it's not a standard part.
What would be peoples recommendation for sourcing service and upgrade parts for a Gaggia lever machine? I'm thinking specifically about things like the insulation spacer that I've seen people fit between the group head and the body, plus the pins and so on for the lever arm.