I know I came in late with advice and haven't spent any time in a manual. So I'm tossing out ideas. Things are starting to sound like a PMT driver issue. Testing drivers by the book is a little tricky and replacement was what we did due to having spares on hand. In a previous post, you mentioned disconnecting the card terminal strip got it reset one time. Not sure if that was a coincident or a clue.
I do seem to be shooting from the hip and it's been quite some time since fighting an EV1, Not very often does the driver fail intermittently. The card on the other hand, more intermittent. If you're savvy with the book troubleshooting, test the PMT driver.