I just swapped the steam and hot water valves, and that seems to help with the leakage. Thanks for the tip. I still wish the non-compression valves from Andreja/Vetrano fit on Anita. That would be a more permanent solution.

I still haven't had any further incidents of low temp at the group since descaling the mushroom, so I'm going to wait to order parts until the problem reoccurs. If and when it does, then I'll give Chris a call and get some new seals, plus maybe a new pressurestat while I'm at it.

OK, this morning the group temp was around 100 degrees after warming up for about 45 minutes. There was a small puddle of water under the group exhaust port, so it looks like the brew valve is indeed leaking. I sent an e-mail to Chris' Coffee service department to see if I can order up a set of replacement seals for the brew valve area.

If you are going to do it, rebuild the whole group and scotch-brite the mushroom to remove the plating. Seals are fine if the brass is sound. Some vendors sell whole kits.

Leaking valves will stall the thermo-siphon. Water can't move through air.

A single clogged feed tube will have the same symptom as a stall.

Use a real scale cleaner, not acid and not vinegar.

I spoke with a tech from Chris' Coffee yesterday, and he agreed that it was a leaking seal that is letting water out of the thermosyphon. He recommended replacing the brew valve, preinfusion valve, and drain valve just to be sure. So I have all of those parts on order from Chris.

Replacing the brew valve should be simple enough, just unscrew the mushroom and pull out the spring and valve, then put in the new valve and spring and put the mushroom back. However, I haven't messed with the lower portion of the e-61 group before. Looks like I'll need to pull apart the discharge tube to replace the preinfusion valve and drain valve. I assume everything just unscrews and comes apart. Any special tips or tricks to doing this procedure?

Chris' Coffee did send a couple of pics of the group that should help explain the process.

Check out the coffeetime link above to see the order of reassembing the lower sections of the e61. You should lubricate the cam when you replace the valves. You reinstall the preinfusion/drain sections with the machine off and the brew lever in the up position so you aren't fighting the cam when you reassemble.

As I mentioned above, soak the old valves overnight in liquid wrench or WD40 before trying to unscrew the pins and remove the worn washers. When you unscrew the pins use gentle pressure and watch closely to make sure you are indeed unscrewing them and not just twisting them until they break off.