[jclark003]

parallel switches comprise a momentary switch on the dash that triggers a solenoid in the ER that closes and ties both banks together. some Tiara models also have an emergency battery interconnect which is a manual switch that connects both banks same as the solenoid.

by referring to the switch only working in one direction, I can only assume he means the momentary dash switch. Some builders rig the switch so that its powered from both banks. That way regardless of which bank goes dead, the switch will still activate the solenoid. It may be that only one bank is supplying power to that switch. Could be as simple as a bad switch or broken wire. Either way as with the rest of the items No big deal. As suggested jumper cables will work. Just make absolutely sure there are no fumes in the bilge when you connect them.

Sounds like a stellar survey