You may also want to check your fuses. Set your multimeter for Ohms, which symbol looks like the horseshoe. Checking a fuse you should get less than 2 ohms, anything over that or if you get Open/OL, replace the fuse. Also check your hydraulic fluid level. We have a decent size fleet of 112 electric ride on pallet jacks here and seems the only thing that ever goes bad on them are the solenoids, handle accelerator/throttle potentiometer and the horn. I have trucks here that are 12 years old and have yet to need to replace the lift brushes but you should still check them because the brushes could be broken if the motor got to hot/overheated. You should also check the lift cut-out switch. While raising the forks there is a switch that cuts the motor out when you reach a certain height. If that switch is broken/shorted it will prevent the truck from lifting.