Upper rack wash arm will not turn .

hello rob – it basically comes down to 2 issues one is not enough water into unit OR the motor is not working properly – an easy way to determine if it is a water volume issue is by simply adding about a quart of water to unit after it has filled and if it operates the upper spray arm then you do not have enough water -if this is the case it is usually a calcification build up in your supply valve and connection under the kitchen sink where the dishwasher supply line hooks up -if you are comfortable with working on plumbing (be sure to check for leaks after reassembly !!) you can disconnect at supply valve and see if there is a calcification build up in valve & if so turn water off at hot water heater. If supply valve is a compression type valve you can remove it and clear calcification or replace it ( even though hot water has been turned of at hot water heater ( be prepared to handle water coming out of pipe after removing valve with towels and a wet vac ) reattach valve after clearing &turn valve to OFF position and turn water back on at hot water heater . Then before turning supply valve back on do same thing at solenoid valve connection where line attaches to dishwasher, then before reconnecting solenoid valve connection put line in an empty 2 liter bottle and turn supply valve on to flush line and check water flow, which should be very strong . Reconnect solenoid valve connection and check operation – if still not enough water going in you may need to replace solenoid valve( part # 154637401 ) by removing 2 screws and fill hose to tub (very simple) .OR IF YOU ARE SURE YOU HAVE ENOUGH WATER TO UNIT AND STILL NOT WORKING UPPER SPRAY ARM then unfortunately you have a bad motor – fairly simple to replace but dishwasher will have to be removed for this repair BE SURE TO TURN OFF POWER disconnect electrical supply +drain hose connection and water supply line then remove dishwasher from cabinet. Lay on its back (careful not to damage anything -a blanket to lay it on would be a good idea ) and simply remove 2 screws from motor retainer plate and slide down motor retainer plate from motor recess and unplug motor connection plug.Then to remove motor just pull straight out of unit then reverse steps to re install new motor ( part # 154859101) and is fairly expensive – but i usually do find water issue most likely cause . Hope this gives some direction at what to do and please be sure to check for leaks very carefully after everything is put back together and good luck