> I have replaced the capacitor on the +5V rail but there is still around 1V
> AC half wave noise on it. Both before the regulator and after the regulator.
> This leads me to believe that I need to replace the rectifier bridge with
> one that can output more current.
The diode bridge has failed, with one diode going short-circuit. This is surprisingly common - far more than failed capacitors which never go unless they get cooked off by a shorted rectifier!
Any very large diode bridge will do. I would tend to make one up out of discrete 10A 400V diodes, but only because I've got hundreds of them to get through ;-)
Gordon MM0YEQ