Do you have a service manual? The FO code means the problem is related to the front trans, I think that 052 code is the trans is not getting a signal to go in forward or reverse. If you have two of these machines I would take the shifter out of the operational one and try it in the machine that is down, it only takes about 10 minutes and that will tell you if it is in the shifter. If that is not it I would say it is a broken wire in the wiring harness or a bad connection somewhere. I'm not a mechanic but I have been around these machines a lot. Electrical issues with the transmissions is the biggest problem I have seen with these machines, usually it was just a broken wire or bad connection in the harness but they can be hard to chase down. Let me know if I can help anymore.
