Picture of Bosch Tassimo Coffee Maker Fix.

     I like my Tassimo but after using it for about a year I discovered that the rubber on the piercing unit wore out and eventually came off completely. This rubber seals the t-disk to the piercing unit so without it the coffee maker is almost useless because it makes a huge mess. I found that replacing the original rubber with rubber “o” rings from the hardware store saves having to buy a new piercing unit, that has to be ordered online for $10.00 + $8.95 shipping. That's $18.95! Hello Tassimo, I could buy a new Mr. coffee pot for that price..... Anyway, here's my fix, I hope this is helpful. BTW, this is my first instructable.

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Step 1: Remove piercing unit

Picture of Remove piercing unit
     This part is explained in the cleaning instructions and also can be found easily online so I'm not going to go into great detail about this. Basically, if you've had this coffee pot long enough to wair out the rubber parts and never taken out the piercing unit for cleaning; then I salute you.

Step 2: Buy "o" rings

Picture of Buy
     Just go to any hardware store and get some new "o" rings. I went to ACE and got one #78 0-ring (stk no. 35715B) which is 7/16 x 1/4 x 3/32. And the other one is a #8 o-ring (stk no. 35725B) which is 9/16 x 3/8 x 3/32. These cost me 75 cents each. And I had a key made.. but I have to take that back because it doesn't work. :(
     All I did was match up the rings they have there with the piercing unit that I brought into the store. Maybe you can find a better match.

Step 3: Put it in place.

Picture of Put it in place.
     I put the "O" rings on the piercing unit then placed it in the machine but you could put them on with the piercing unit in place. One thing to watch out for is when you take the piercing unit off the machine keep your finger over the "O" rings or they may fly off into the back part of the coffee maker. That happened to me and I had to tip over the entire coffee maker and shake it out.

Step 4: Drink Coffee!

Picture of Drink Coffee!
     I ran a few cleaning runs with the cleaning disk before actually using the repaired piercing unit. The next and final step was to make coffee!

themonroes4 years ago
Thanks for the instruction. I haven't tried it yet but I'm on my way to Lowe's right now. Is it still working okay?
markie161 (author)  themonroes4 years ago
Still works! I replaced the rings cause they flattened out, not a biggie though.
I just got one and it has wster in the back filled up but as soon as i opwn the lid and close it it just keeps blinking red with the fill water sign please help how do i fix it. I always wanted one now that i got a used one it dont work n i dont got $ for a new one. Thanks
markie161 (author)  susan.logsdon.319 months ago

Make sure the black disk in the water tank floats up when water is in the tank. This is a magnet that tells the machine when water is in the tank. That's the best I can tell you without knowing any more.

RonW111 months ago

Thanks for the info about the o-rings. I also had the same problem but my gasket seemed to be fine so I removed the piercing unit and used a paper clip, and a small brush to clean out the years of gunk that blocked the discharge hole, It now works fine.

bschuhma1 year ago
Thanks for the tip, Markie161! I've had my Tassimo for years and NEVER popped out the piercing thing. It all started leaking the other day... I found your 'able and am making great coffee again! Appreciate it! :-)
mungaman4 years ago
Thanks! I lost the o-rings so you saved me a lot of time!
themonroes4 years ago
I called Tassimo customer service this a.m. before I went to Lowe's and asked about the potentially defective piercing unit. The obviously-not-an-American agent said she would send me a new one for $9.99 and no shipping charge. I said I was hoping not to get charged since it appeared to be defective. She said, "no problem, I'll send you a new one at no charge." I asked about the shipping charge and she said "no problem, no shipping charge and it should arrive in 1-2 weeks." Needless to say, I didn't go to Lowe's!