My miele cva 4075 is not heating the frothed milk or coffee up as well any more...sometimes a Fault 73 shows on the screen..i have cleaned the brew unit with tablets and water etc...what should i do next?

Question edited for clarity, add maker, 'make model (what it is)' first 3 words and add magic word.
Question moved to maker category.

These machine need dealer service every 9 to 18 months depending on use. They don't tell you this when you buy them. Your leak is almost certainly worn O-rings in the brew group or the pump.

https://www.google.com/search?q=Miele+CVA+4075+leaking

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This particular Miele is featured here on Fixya a LOT. These machines need dealer service every 6 to 9 months. They don't tell you this when you buy them! You just pick them up, take them to a service centre and collect it a few days later, fixed and with all new O-rings and seals.

Fault 73.

https://www.google.com/search?q=Miele+CVA+4075+coffeemaker%27s+Fault+73

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(3) I have fault 73 on Miele coffee machine - YouTube

You may have abandon the repair effort and purchase a new replacement.

Defective brew unit drive.
Replace brew unit and drive.

Greetings from
Certified Miele Tech

It needs the brew unit cleaned - descaling is mainly for the heaters. The Brew unit tablet (the one the size of a sweetart) is used to clean just the brew unit. In the maintance menu your will find clean brew unit - follow the bouncing ball

http://mielerepaircenter.com/miele-coffee-maker-repair

It sounds like the venturi tube is blocked. Have you ever removed the frothing unit and cleaned in manually? I have a model 4085 and I can reach under where the milk exit tube comes out, twist anti-clockwise (if you are looking up at it) and the whole assembly with the inlet and outlet tube comes out. These pieces can then be individually taken apart and rinsed thoroughly with warm water. If you put it back together (don't forget to twist the connector that locks it back in) and the milk still doesn't froth, take it out again and use a small needle to clear the top of the clear venturi tube which sucks air in to do the frothing. If it is really badly gunged up it might need to be replaced, but mine is 5 years old and still going with regular rinsing. My whole brew unit had to be replaced after 4 years at a cost of about GBP 200, but that's another story.

F73 is a bad brew unit. The cva 4070,4075,4060, and 4066 are designed to use espresso beans.
If you use an oily bean such as Starbuck's french roast, it will clog the filter in the top of the brew unit. If you catch it in time, you can just replace the brew unit. If you run the machine with a clogged filter long enough, you have to replace the brew unit and gearbox together.
Sometimes if you work with the tech support department, they will send you a brew unit to install yourself. If you live in an area that has Miele factory support, you may just want to get a service call. It is very important to rinse the brew unit every 24 hours, and to use the cleaning tablets in the trap door( not the descaling tablets) if not, the coffee oils build up and turn into a tar that will clog the brew unit. They run about 300 dollars so they are worth doing the maintenence on.

I have had the same fault 73. Miele is coming out to replace the drive and the brew unit. SHould be a $700 repair. Thank God for warranties. I'll et you know the end result once repairs are complete.