I noticed a strange lever behavior on my Bricoletta a few days ago. When I move the lever to the off position (0°, pointing straight down), it pops up to about a 20 or 30° position (with 'on'/horizontal = 90°). It's not enough to activate the pump with machine on or allow water to flow through mains pressure with machine off, but it's definitely different than what it has done in the past ... which is resting nicely at a plumb/down position.

Has anyone experienced this on an E61 group? I decalcified it maybe 2 months ago, and regularly backflush with detergent. I'm mostly a) curious why it happens, and b) wondering if it's a problem (if it's putting wear on some part, or ...).

Open the grouphead and check for wear on the plungers or the cam

Have you noticed a weakening of the exhaust sneeze when you back flush? On my (former 6 year owner) Bricoletta first couple of years I detergent back flushed too often (weekly, without lubing cams and pins after - didn't know any better at the time) which removes lubricating oils causing relatively rapid wear of the cam pins, especially the lower pin. Eventually got so 3-way didn't function at all resulting in no pressure release after shot and dreaded PF sneeze. Replacing the (13mm on Bric') lower cam pin fixed the problem, upper pin and cams were ok.

Haven't noticed a weakening in the exhaust 'sneeze', but that would likely a very gradual change, making it difficult to notice. But your post describes precisely what I've been doing ... weekly detergent back flush, with no lubricating (hey, the 2-page manual didn't say anything about that!). So I assume I'll have to do what you both suggest, and open the group head.

The lever position is actually fine again today, no idea why. But if it's a worn cam or pin (which, looking at your posts and some group head schemata I think it is), the issue will probably return soon. So expect a post pleading for help when I've opened the mushroom and don't know how to put it back together in the next few weeks

FYI you get to the lower cam pin removing the bottom exhaust tube, not mushroom.

Randy Glass has written an excellent "how-to" as regards disassembling the E-61 grouphead. See this:
http://www.espressomyespresso.com/ and go to the "How-To", page 19. While it does illustrate the Vibiemme grouphead, the upper portion, the "mushroom" is the easy part of the disassembly. If you are doing this for the first time, it can be a little intimidating. However, it is pretty safe to take it apart, see what parts you need and reassemble. See parts below:

Thanks, Compass and erics. I've looked at those how-to guides; they're fantastic ... as is his video with the split group head that shows how everything works inside. I'll make sure to review all of them when I get some time to take this thing apart.