Our definity has been acting funny the last couple of weeks-8400's will only pick up lines if they are programmed as 7406's, the test light just blinks if they are programmed as 8400's. I've tried to refresh terminal parameters but it won't -I guess since the tn754 is the only cards that will pick up lines on the 8400's. I've switched cards, power supply, etc. no change. We've had the same switch for 4 years and it just started this---any ideas???