Discolorization(orange) inside coffee maker.

I'm sorry to hear that you're having trouble finding replacement water filters for your Cuisinart DCC-690 coffee maker.
After some research, it appears that the DCC-690 model does not have a specific water filter that is designed to fit it. However, Cuisinart does offer a universal water filter that can be used with any of their coffee makers.
The Cuisinart DCC-RWF replacement water filter is a universal filter that is compatible with all Cuisinart coffee makers that have a water filter. It is designed to remove impurities from tap water, such as chlorine, calcium, and other minerals, to improve the taste and quality of your coffee.
You should be able to find this filter on Cuisinart's website, or at a retailer that sells Cuisinart coffee makers and accessories. It is important to note that the filter should be replaced every 60 days, or after brewing 60 pots of coffee, whichever comes first.
I hope this helps!

In the first instance you can try cleaning and descaling it. The whole tank with float is available as a spare pare if this is your model.

https://www.google.com/search?q=cuisinart+coffee+maker+float+replacement

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It is endemic to this unit - condensation builds up in the grind chute, which makes the grinds stick to the walls of the chute. Decalcifying with vinegar/water helps, but only in an indirect way - by keeping the inside tubing clean, decalcifying generally allows the water to flow through the machine without obstruction. Inside tubing that has calcium, lime deposits built up obstructs water, and makes it flow through the machine slower - when water flows more slowly through the machine, the machine steams off the water at a higher rate, hence more condensation builds up in the grind chute walls.

Generally, i have found all Cuisinart coffee and espresso makers to be high maintenance to a greater or lesser extent, but the Grind-n-Brews have the highest cleaning/maintenance requirement.

Cuisinart – leaking from bottom
There is a tube inside that is melted, damaged - cannot get this part from manufacturer. I would call Cuisinart to see if you are still in warranty.
Here is the basic troubleshooting for the Cuisinart coffee makers:
Make sure all baskets are in proper place – especially if unit is beeping.
Do not use a paper and a gold-tone or other permanent filter at the same time.
Unplug for LONGER THAN 15 full minutes to reset.
Clean by brewing 2 oz of distilled white vinegar/2 oz water.
If these methods fail, the unit probably requires replacement – call Cuisinart as they have a longer-than-standard warranty.
-Tha Mp3 Doctor

Cuisinart DGB-600 replacement charcoal water filters is Cuisinart DCC-RWF 6 pack charcoal water filters, 12 filters.

Replacement time. a certain percentage of thse have this problem. There is a small, non-replaceable tube in the inside toward the bottom that has become melted/damaged.

This happens when the machine needs cleaned. Fill coffee maker with white vineger instead of water. Turn grind off, make sure empty pot is in place. Brew a pot of hot vineger. Repeat. Brew a pot of hot water. Repeat. This process removes mineral buildups inside machine. If you have access to filtered water, start using that to brew your coffee. I do and probably do this process 1 per 6 weeks.

Use a Torx T-9 tamper resistant tool to remove the screws on the bottom and access the inside of the machine.

The water hose on the bottom of the coffee maker is worn, due to the heat. It needs to be replaced. this is the second time for mine.