Hi Everyone,
For some reason, every time I try to lightly clean the grouphead on my Oscar, it creates this problem where the portafilter will no longer lock into place securely. I'm pulling my hair out! I've carefully inspected the rubber gasket, and it looks to be intact and seated properly. I've done nothing whatsoever to the portafilter. It's a complete mystery to me! It works just fine when it stays grungy, but that's totally gross! Usually, I can work it back and forth, and it'll eventually go back to how it was before, but when cleaned it yesterday, it was the worst yet. It wouldn't move more than about 3/4" towards 'locked'. I know I'm not supposed to backflush it, but I occasionally use the blind filter to just loosen the grounds from the screen and the track where the portafilter goes. Is this wrong? This last time, I felt the exact moment when it changed. I was moving the portafilter back and forth slightly, but not enough to lock it in. It suddenly "grabbed" the portafilter and sucked it to the grouphead, and then it was really hard to get it off. Afterwards, it would barely go back on and lock in. I know this is a popular machine. Has anyone else had this problem? Any tips on safely cleaning the grouphead?

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Just a guess here......are you sure the portafilter is locked in tight at all times while you're backflushing? I'm thinking that some water may be pushing up under the top side of the gasket. I don't think it's a good idea to move the portafilter back and forth while the pressure's on, especially with the blind filter in place.

I'm curious why you say "I know I'm not supposed to backflush it".
Huh. I've used an Oscar a couple of times and without really thinking about it I treated it like a larger commercial machine (an Aurelia or a La Marzocco GB-5), by which I mean I backflushed to clean out the solenoid (http://en.wikipedia.org/wiki/Solenoid_valve). I don't know if the Oscar even has that kind of valve in it (http://www.nuovadistribution.com/oscar.html); if the machine came with a blind, then I think you should use it to backflush. I own an Olympia Cremina and it doesn't have the valve, so backflushing is unnecessary. I just keep the screen and steam wand clean.

Let's try this: clean it less often. We are dealing with metal on metal action, so I think a thin (read: not dark and gunky) layer of espresso is both acceptable and good for keeping the metal-on-metal connection lubricated. Yeah, if it's caked clean it, but otherwise leave it alone. Keep in mind that metal expands when exposed to heat and contracts when it's cool. If you are using the Oscar once or twice a day and then cleaning it, it's possible that the heating up and cooling down process (as opposed to keeping the machine on, and thus at a consistent temperature and metal at a consistent size) has warped the portafilter, gasket casing or both. Use a mirror or look the beast right in the mouth and find out. It might just not fit anymore.

Good luck!
ChrisG


BTW, I don't see anything wrong with using a blind to "jiggle" loose grounds from the screen and gasket.
This happens to me some times on my commercial equipment if water gets under the gasket when I am backflushing. What I have found to work best is to pop the basket out of the portafilter and insert the PF into the group. Crank it around like it had the basket in there. The small amount of extra space caused by the lack of PF basket will allow you to put it into the normal locking position (or slightly beyond). After I do that a couple of times to get the gasket back into place I insert the basket and do the same thing again. This usually solves the problem for me.

Sounds to me like water is just pushing the gasket out of the group slightly.

-bry
Thanks, everyone. Bry, your trick usually works, but this time, it's pretty bad. It's GRADUALLY, bit by bit, day by day, loosening up again.

I think you guys are probably right about water getting behind the gasket. I can't think of anything else it could be. Visually, there is nothing out of the ordinary going on, and water and air are invisible, so it must be one of the two!

BTW, Bob, the user's manual doesn't even mention backflushing in their cleaning/maintenance instructions, so I think it's best to follow their recommendations. Some machines aren't meant to be backflushed, like Chris touches on in his post. Although, it did come with a blind filter, so there are some mixed signals there.

Chris, in response, this machine stays on constantly, and it is used pretty heavily every day in a large office setting, so the temp of the metals stays constant. It works reliably every day til get crazy and decide to clean it.

Thanks for the input, guys! Good stuff!
It came with a blind?
Backflush away.

The brewing guide included with a Chemex never actually mentions adding hot water, if I remember correctly. Sometimes guides just really suck.

-bry

Jennifer Graham said:
Thanks, everyone. Bry, your trick usually works, but this time, it's pretty bad. It's GRADUALLY, bit by bit, day by day, loosening up again.

I think you guys are probably right about water getting behind the gasket. I can't think of anything else it could be. Visually, there is nothing out of the ordinary going on, and water and air are invisible, so it must be one of the two!

BTW, Bob, the user's manual doesn't even mention backflushing in their cleaning/maintenance instructions, so I think it's best to follow their recommendations. Some machines aren't meant to be backflushed, like Chris touches on in his post. Although, it did come with a blind filter, so there are some mixed signals there.

Chris, in response, this machine stays on constantly, and it is used pretty heavily every day in a large office setting, so the temp of the metals stays constant. It works reliably every day til get crazy and decide to clean it.

Thanks for the input, guys! Good stuff!
Hey Bry, if I break it, will you buy me a new one??

Bryan Wray said:
It came with a blind?
Backflush away.

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