At wits end...Old Marquis Spa causing grief! Model 3000 A, 220vac, My heating elements wouldn't come on, found my pressure switch plugged with calcium, wouldn't close to operate thermostat. In the process of changing that switch, I managed to break a contact on one of the two pump relays. It is a DPST latching relay that is apparently discontinued. Thing is, on the other pump relay, that contact is spare, so I figure, no worries, I'll just swap the relays. Except, relay with b/o contact no longer latches. I am an electrician, and for the life of me can't see why they put a latching relay in to begin with! However, with one latching and one not, I'm a bit concerned about just swapping them and firing it up... I have the elementary diagram and would love to fax it to whomever might be up to this challenge! Please Help...

could you perhaps explain this "latching" relay? Are you talking about it is holding due to constant power once energized, or is it a mechanical relay that latches, and must be manually reset, or ?

If you could post the schematic here, you might be able to find someone that can help you out.