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The concaves in our 2388 will not move using the switch in the cab. I can manually adjust them though. What is the most likely cause of the electric adjuster not working? Thanks in advance.
 

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most all units use a dc volt electric ram that changes the polarity=positive and negative, wire feed to the electric motor that drives a screw assembly. often there will be relays that are in the system, usually the bosch cube relays. these can fail from vibration and arced and pitted contacts. their purpose is to change the polarity as well as provide enough amperage to the motor without going through your switch in the cab. the switch can fail also. go directly to the wiring junction at the ram motor and disconnect it and then with some heavier gauge wire provide power with a battery to each terminal, then change the polarity and see if there is any action. if the motor drives you have eliminated it, then check for voltage to the other side of the connection while your buddy actuates the cab switch, if no power check for the relays action, the relays can still sound like they are working and provide voltage, but if the contacts internally are pitted they will not provide current/amperage to drive the motor. the in cab switch will have six wires that are specific to location, so make sure if you replace it they are placed properly, there will need to be positive and negative wires to the switch in the center terminals and then each side of the rocker will have pos and neg also, but opposite placement. it is a fairly simple design, but any breaks or resistance for voltage and current wreaks havoc.. good luck, first check the relays and location of them, these relays are typically about 5 bucks each and i carry several as they are used in a lot of different applications...
 

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The gears can strip out too, stick your head under the shield and inspect the gears. Mine has teeth that would be at home picking a banjo, so they are getting replaced. But that was causing my issue.
 

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it could also be a lubrication problem with the gear shaft or the worm-screw shaft -- if they are squeaking some graphite spray will help . Also had issues with the little motor that drives the large gear as it will just gum up with dust and crap and just barely wants to turn . There I'd suggest either replacing it or taking apart and cleaning and re-lubing . Just a word of caution is that if you put it back together wrong the motor will run backwards possibly because the brushes are in the wrong position to the magnets .
 

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rickfly gave you what you need. it is not uncommon for those motors to fail, we had one fail on a 2388 and the electric motor on the rotor speed and fan speed fail also on a 1680, but rickfly gave you very detailed instructions that should easily let you figure out where the problem is good luck
 

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it could also be a lubrication problem with the gear shaft or the worm-screw shaft -- if they are squeaking some graphite spray will help . Also had issues with the little motor that drives the large gear as it will just gum up with dust and crap and just barely wants to turn . There I'd suggest either replacing it or taking apart and cleaning and re-lubing . Just a word of caution is that if you put it back together wrong the motor will run backwards possibly because the brushes are in the wrong position to the magnets .
This has been my experience, buying several secondhand 21/2388 combines, if u blow of and pressure wash off all the gunk, then lube it good.. Play with switch back and forth it will free up, at least in my experience
 

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check the brass bushings on the shaft that is connected to the electric motor that controls the rotor speed, engine compartment
 
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