I have a 8900 Pallet Jack and E107 relates to the main contactor it could be lots of things wires loose,tips being dirty, not making contact, take it apart and see the pattern on the tip it should be like a diamond pattern....order tips kit.... look their online sales number online to order and get a part number for the mean time you can clean with contactor cleaner, as for the other code showing C128 always mean something wrong with the handle. (I don't know the differences between this two models but I bet is the same). good luck

Adding to that E107, can cause other faults like undervoltage.