Dometic model ndr1292.my water tube for ice maker is falling apart.how do i replace it?

NDR 1292 amish style cooling coil replacement - YouTube

? 8:13
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Oct 13, 2012 - Uploaded by taintedcrimsonwings
Step by Step instructions for replacing a Dometic NDR1292cooling unit. ... RV Refrigerator Cooling Unit Replacement Part #2 Installing The ...

is water line connected, and turned on??? if so, check for a plugged filter, kinked supply line.

Good day,
Sounds as if the fill tube to the ice maker is either plugged with ice, broken, or adjusted improperly.
Remove the ice maker, then the fill tube needs to be inspected closely for the issues above.
As well, the fill valve in the bottom rear of the machine might not be shutting off completely after filling the ice maker well. If that is the case, the valve is non serviceable and must be replaced.

Here's a link to number to call for info on replacement parts available.
http://www.dometic.com/enus/Americas/USA/Customer-Support/Spare-Parts/

What you think is probably correct. Water valves can seep water and freeze the fill tube. Remove the ice maker and the fill tube remove ice from the fill tube and replace the water valve.

Replace the water inlet valve . Water is seeping thru the valve when closed . Drops of water seeping thru and freezing inside the fill tube . After replaceing valve , be sure to remove the ice from the fill tube .

http://fixitnow.com/wp/2008/08/11/how-to-repair-a-leaking-evaporator-in-your-refrigerator/
go to that link and solv your problem

Not getting enough water into the ice maker. Could be a partially frozen supply line, restricting the total water input, or it could be that the timer needs to be adjust.

If the water supply tube to the icemaker is frozen. It will be a white rubber tube on the right side of the icemaker. Warm it with a hair dryer, remove it from its aluminum tubing, and make sure there is no ice all the way back to where the supply tube comes from the water valve. After thawing, your icemaker should start working again.

Now..... why did it freeze? Most likely, there is a restricted airflow to the back of the unit, which is need to keep that aluminum supply tube just warm enough to assure all the water flow OUT of it into the icemaker, and doesn't freeze up on contact. Make sure your coils and the airspace under the fridge are completely clean (vacuuum them well) and it should cure the problem.

To adjust the timer, follow the instructions here http://www.acmehowto.com/howto/appliance/icemaker/diagicemaker.php