After installing new batteries I checked the voltage at the battery 24v circuit and it was reading about 60V. I immediately disconnected the solar regulator and it dropped to 26V. I repeated this to be sure. So it looks like the problem was caused by the solar regulator failure. I have been advised to replace it with a Blue Sky unit.
Re. charger, position 1 (lead acid) on my Dolphin charger conforms to the voltage limits specified on the batteries.
Thanks for all the feedback.
Amel 54 Ya Fohi #98