I have a 20 year old Autohelm ST 30 depth and speed unit that works like a champ, until yesterday when the depth signal stopped and shows 0 feet with the feet indicator flashing. The manual says it is a sign of a bad transducer or a cable or connector issue. Cable looks good, reset the connector which also didn't look bad but still no depth. Any ideas on where to find a replacement transducer. Now owned by Raymarine but their website doesn't show parts that old.