I have an RM 6000 that is throwing a code 815. After following through the trouble shooting steps provided from the crown book and running other diagnostics on the unit, Code still persists. Forks will extend and retract while calibrating but does not accept calibration and stops working after leaving calibration screen. Forks will retract but not extend! Access 4 has been replaced and programmed, RPS3 has been replaced, coil to reach and extract has been replaced, and control handle has been replaced. All settings have been compared to another RM6000 and everything matches. Any suggestions will be greatly appreciated!