If it is a 24 volt battery (a thing Ididn't know existed -- any time I have
come across 24 systes they have always been 2x12 volt batteries) it needs
about 28 volts output from the charger, and the fully charged battery should
show about 26 volts acroos the termminnals of charge.

It looks to me like one of the dodes is blown in the rectifier pack, i
would just replace with a single solid state rectifier.