We use a GM 10SI alternator on a 64 Dodge NSS car and over the last 10 years we have replaced 3 of them that fail to charge after the Winter storage. The battery is disconnected for about 5 months, so the alternator is not receiving power during this time. I was told that if left connected, the small leakage current through the diodes is enough to keep the field magnetized. There is a procedure to remagnetize the field with the car running by pulling the plug on the alternator and momentarily touching the R terminal to the positive battery terminal, but this hasn't worked. Any suggestions?