Replacing mechanical Latching Relays with dual coil relays...

Anyone have experience with dual coil latching relays? I'm trying to replace old (1950s) Guardian latch relays as used in 1950s style jukeboxes with more modern two coil latching relays but have had trouble with some relays going to an indeterminate state if the power to the coil is  below optimum.
What I actually need to do is a circuit that only allows the Latch/Reset coils to trip when there is sufficient voltage and current available...
This somewhat plays into the discussion on DC relay latching voltage thread and I'm wondering if the Zener diode across the windings or in series with the windings might help my design.
As for the old original relays, the contacts are getting so pitted they can't be saved and Guardian hasn't made this coil assy for decades. They don't turn up on eBay either.
Thanks,
John :-#)#
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