Jeremy,
Welcome to the WFM forum!
You will find a section in the engine manual for your tractor that covers the alternator -- there is no real detail in the service manual, TM1591. I do not have the diesel, my 322 tractors are the gas version of the Yanmar 3 cylinder, but the CTM12 engine manual for that engine covers both the Nippon Denso 35A and the Kokasan 20A alternators in some detail regarding disassembly, repair and reassembly.
You did not mention how long you have had your tractor, but getting the operator's manual, technical manual and engine manual would be a good investment in your ability to minimize the costs associated with unnecessary parts replacement. The satisfaction of doing it oneself is what many members here also relish...
Chuck