18 yr old kenmore electronic dishwasher has stopped filling at same time as aerators on faucets filled up with sand and gel particles. Is there a filter to remove/replace or is this a disassembly job to clean out the debris from the water line somewhere inside the workings of the unit? I can't find an online parts manual at this time.

Hi and welcome to FixYa I am Kelly.

If you had sand and gel in all of your plumbing... you will have to remove the water inlet valve. As a repair professional I would first attempt to power the solenoid using a test cord and use compressed air to REVERSE flow the inlet water valve so that all the particulate matter exited the same way it entered the valve. If that did not clear the problem due to labor costs I would replace the inlet water valve. Some models you can dis-assemble the inlet water valve once removed and clean them. Others are disposable. Without your model number I can not make that determination at this time.

What you must do is first remove power.... then turn off the water supply... remove the water valve and attempt to clean it. Reverse flow is best but the solenoid must be powered. You can make a test cord to plug into a wall outlet knowing that the 2 terminals will be live / powered during cleaning with air. You introduce air into the oulet side / plastic manifold fitting with the valve is powered to remoce the debris.

Your parts can be found at http://www.searspartsdirect.com Then upper right side of the page enter your model number.... choose model search and then click go.
A model number will look like this: 665.1675592

Average Kenmore dishwasher water valve is PN 8531670 / $49.34
http://www.partselect.com/PS887858-Whirlpool-8531670-Water-Inlet-Valve.htm?SourceCode=3&SearchTerm=8531670

$39.78 (below)
http://www.appliancepartspros.com/part_details.aspx?part_id=3178610&pn_=8531670

$43.08 (sears parts direct)
http://www.searspartsdirect.com/partsdirect/part-number/8531670/0022/665?pathTaken=partSearch&filterPart=&pop=flush&prst=0&shdPart=8531670

None of the replacement inlet water valve parts above are repairable.

Thanks for choosing FixYa,
Kelly